The cards were stacked against him. The legacy of Vietnam and the Yom Kippur War led to a massive debt, and an oil embargo from OPEC. This led to high inflation, high unemployment and constrained federal budgets for the first time in ~40 years.
Arguably he saw the correct way out through innovation and American energy independence but the technology wasn't there yet and the electorate had little stomach dealing with high unemployment and high inflation through austerity for the length of time needed.
He was also perhaps too principled for Washington politics, and he routinely got his ass handed to him by his own party in Congress which had no desire to curb spending on even the most obviously wasteful programs.
But these are all excuses and as President you don't really get to make excuses. As much as I admire and respect the man and support his vision for America, the reality is things just didn't work out for him as president.
