This mistake of yours is also the mistake of so many people in the crypto space, so many people did not buy Bitcoin when the price was around $1 - $1k till $20k and as a matter of fact, many people bought Bitcoin when the price was $100k last year, that's when they probably hat the guts to buy some.
Many people didn’t buy bitcoin when the price was still so cheap, they didn’t believe bitcoin price will get to the price that bitcoin is right now and that was the reason why most people didn’t invest in bitcoin when the price was still low.
Just few people were able to invest in bitcoin when the price was so low, and some people didn’t even get to know about bitcoin early. Even right now there are some people that haven’t heard about bitcoin before, some don’t also have trust in bitcoin and they just observing bitcoin price. I didn’t get to know about bitcoin early, and when I knew about bitcoin, I wasn’t financially stable, but we can invest at any time, when it’s comes to bitcoin investment you can’t be late.
Besides those who did not buy Bitcoin when it was cheap because they did not trust it, there are also many people who bought Bitcoin at a low price but could not hold onto it until now. Many people had the opportunity to buy bitcoin at prices even below $1k, but they sold it after it doubled or tripled. Only a select few have been brave enough to hold onto them until now.
Overall, investing in a new currency and holding it for many year is not an easy task. Therefore, there is nothing to regret if we did not buy it sooner or weren't brave enough to keep it until now.
Furthermore, as long as the market exists and the price of Bitcoin continues to rise, opportunities are plentiful. So there is no need to regret what is already happened.