I don't know if I would go as far as the full theory of Kondratiev cycles, but there certainly are both business and consumer cycles and there will be economic downturns (and upturns). But things like the Crash of 1929 and the Great Recession aren't set in stone either. For example:-
1) If Hoover had permitted Mellon to free up the money supply somewhat after the 1929 Crash (as Mellon wanted to do OTL), there might never have been a Great Depression just a recession and the US economy starting to recover by 1932. The 1929 Crash would still have been a thing but wouldn't have had any graver long term historical resonance than the 1907 Crash;
2) If Russia hadn't gone Communist at the end of WW1, hadn't defaulted on Tsarist bonds and was fully engaged in the global economy, the business cycle and consumer cycle would still most probably have delivered a Crash and, at the very least, a recession. But this would likely be triggered in 1931 or 1932 and not 1929 due to a larger global market;
3) If Roosevelt had been assassinated in 1933, contrary to much AH speculation, the New Deal would have probably worked better under Garner who had a better instinctive grasp of economics than FDR and opposed those elements of the New Deal which modern economists believe to have delayed recovery and prolonged the Great Depression; and
4) Some technical innovation being introduced ten years earlier (e.g. commercially viable TV around 1921) probably generates a consumer electronics boom that would take the worst effects off the Great Depression.
1) If Hoover had permitted Mellon to free up the money supply somewhat after the 1929 Crash (as Mellon wanted to do OTL), there might never have been a Great Depression just a recession and the US economy starting to recover by 1932. The 1929 Crash would still have been a thing but wouldn't have had any graver long term historical resonance than the 1907 Crash;
2) If Russia hadn't gone Communist at the end of WW1, hadn't defaulted on Tsarist bonds and was fully engaged in the global economy, the business cycle and consumer cycle would still most probably have delivered a Crash and, at the very least, a recession. But this would likely be triggered in 1931 or 1932 and not 1929 due to a larger global market;
3) If Roosevelt had been assassinated in 1933, contrary to much AH speculation, the New Deal would have probably worked better under Garner who had a better instinctive grasp of economics than FDR and opposed those elements of the New Deal which modern economists believe to have delayed recovery and prolonged the Great Depression; and
4) Some technical innovation being introduced ten years earlier (e.g. commercially viable TV around 1921) probably generates a consumer electronics boom that would take the worst effects off the Great Depression.