It's hard to say exactly when Bitcoin will hit $1 million, but many analysts and investors believe it could be within the next decade, i think it will depend on a few factors like-
Institutional Investment and Legal Legitimacy.If more institutions and governments accept Bitcoin as an asset and clarify regulatory policies, as well as if the government enforces favorable regulations for Bitcoin, it can attract more investors, leading to widespread demand and an increase in value over time.And can be $1 million at a time very quickly.
This should be the concise explanation to this subject because the prospect of bitcoin depend largely on how well bitcoin is able to penetrate the day-to-day activities of a large percentage of human population. In other words, if mainstream adoption of bitcoin happens very fast, then the price will have no option that to rise due to increase in demand and the fact that bitcoin have a fixed supply. Until this happens, bitcoin will rise but not exponentially. Hopefully we will see some positive news in the aspect of mainstream adoption before the end of the present administration of the US that seems to be pro bitcoin.