The answer depends on the objective.
If the objective was to stop the axis winning by keeping Britain and its Empire in the war while at the same time reducing the UK from a flagging super power to near-bankruptcy then the right amount was clearly given.
In light of Roosevelt’s underlying antipathy towards Britain it would appear likely that this was his intention. That same antipathy lead to his belief that Britain would be a greater threat to US security than Russia after the war.
From a British perspective, those who lived through the war can harbour some bitterness over our country’s emasculation. They witnessed first hand a dramatic decline in Britain’s standing and it’s always good to blame someone else! However, they forget that this US support (despite the strings) was critical in helping the UK avoid a far worse fate.
Machiavelli was an Italian, and lived at a time when Italy had been divided into relatively small pieces. The Machiavellian tactics he described were not intended to exist in a vacuum. He felt that such tactics were tools to be used for a higher purpose: the purpose of re-unifying Italy. Often when reading about how a collection of small European states had become united into a single nation, one reads that Machiavellian tactics had been used. Machiavellian tactics appear effective at achieving their desired goal (of unifying smaller states into larger nations). I would also argue that traditionally, British leaders were no strangers to Machiavellian tactics, and used these tactics to build and maintain their empire. Machiavelli’s underlying goal had been to do what was best for Italy; just as British leaders had in the past often been motivated by the desire to do what was best for Britain.
Traditionally, Britain pursued a policy of balance on the Continent. If there was a European struggle between two nations or two alliances, Britain would side with the weaker party, in order to prevent any one nation or entity from gaining too much strength. The British understood that a divided Europe posed a much graver invasion risk to Britain than a Europe united under any one banner.
The Soviet Union had about 2.5x the prewar population of Germany. In 1942 the Soviets produced 3x - 4x as many land weapons as the Germans, and nearly twice as many military aircraft. (Germany caught up by 1944.) The Soviet Union also had a much greater land area than Germany, and much better access to farmland, oil, and raw materials. On top of all this, the Soviets had signed a defensive alliance with the French in 1935. In the cold war between Germany and the Soviet Union, Germany was clearly the weaker party. So why did the British abandon their traditional foreign policy of pursuing European balance in favor of a pro-Soviet, anti-German foreign policy? That abandonment cannot be explained in Machiavellian terms, because a Europe dominated and controlled by the Soviet Union and Joseph Stalin did not serve Britain’s national interest.
Prior to the outbreak of hostilities in 1939, the Soviet Union had murdered about 1,000 times as many people as had Nazi Germany. Britain’s pro-Soviet, anti-Nazi foreign policy cannot be explained in humanitarian terms. Nor did that policy stem from an altruistic desire to help the Polish. British and French leaders had lied to the Polish, and had promised them that France would launch a general offensive against Germany within 10 days of mobilization. The promised offensive never materialized. Lying to one’s own allies would typically be considered a Machiavellian tactic. But that tactic did not serve a Machiavellian purpose, because the outbreak of hostilities between Germany and Poland did not serve the British national interest.
Prior to the start of WWII, Chamberlain and Stalin had discussed the possibility of ganging up on Hitler. Stalin expressed openness to the possibility. But he said that his price for entry would be the annexation of the eastern half of Poland, and all of Finland, Estonia, Latvia, and Lithuania. I don’t recall whether he did or did not also demand a slice of Romania. Chamberlain refused this proposal. In a speech in the House of Commons, Churchill said that Chamberlain had made the wrong decision, and that Stalin should have been paid the price he’d asked. Churchill’s motive for wanting to enter WWII had nothing at all to do with protecting Poland, or any other nation in Eastern or Central Europe, from hostile foreign domination.
In a modern Western democracy, running for political office is very expensive. Politicians typically require large donations from very wealthy people. In the absence of such donations their political careers typically come to a screeching halt. We typically spend far too much time analyzing what makes politicians tick, what they are thinking, and why they make the decisions they do. We are acting as if they are the people who wield real power. I would argue that the most powerful category of people are not the politicians themselves, but rather the economic elites who fund those politicians’ campaigns. A standard-issue politician is little better than a paid shill for those economic elites.
A hundred and fifty years ago, Britain’s economic elites probably wanted what was best for Britain. But at some point, Britain’s national interests ceased being a relevant consideration for those elites. The disappearance of patriotism and loyalty among Britain’s ruling economic class explains both the pro-Soviet, anti-Nazi pre-war foreign policy, and explains Britain’s loss of its empire in the postwar period, and explains the decision to flood itself with Third World immigrants in the postwar era.
Ants are very loyal to their colonies. But sometimes loyalty is not enough. For example, a red ant queen will use scent to disguise herself as a member of a colony of black ants. She will invade a black ant colony. Because she has disguised her scent she is unmolested by any of the black ants. She heads straight for the black ants’ queen, kills her, and takes her place. Having done this, the colony’s black ants loyally serve their queen’s murderer, and the killer of their own genetic futures. Gradually, the red queen’s offspring replace the black ants to whom the colony had once belonged.