Except the tax cuts DID pay for themselves. Government revenue rose 40% under Reagan. Spending rose 100%. So the tax cuts absolutely “paid for themselves.” They did in the Kennedy years as well. They did not in the Coolidge years, but revenue shrank only a tiny bit while the money supply shrank a lot, so in REAL dollars they paid for themselves.
What we admirers of Reagan don't like to remember, though, is that, beginning in 1983, the Federal Reserve began inflating again. Yes, the tax cuts certainly did spur the economy, but cheap credit supported by newly-printed money really turbocharged it.
That particular bubble ended with the Savings and Loan debacle. Eventually we inflated our way out of that mess, too.