We regret about missing Bitcoin, then about XRP then about Ethereum then Doge then Shiba then Pepe (these are some top of my head and from what I've come across in my crypto term).
Point being there are always new opportunities and dwelling on regrets is futile.
If it not for us it will never be for us, that's the thing we will be carried away by fomo, we will always regret something. But then to make things right we should always monitor what is trending so we can follow and we can understand what is happening. Making a research about something is worth it, because we can found gems and when we found it, we will never feel fomo. About bitcoin it is not too late to buy as well as to eth. Never in my life I regret buying bitcoin whatever price it could be.