Having a feeling of regret is normal and it is something everyone feels when they miss opportunity. I have regretted many things including not holding Bitcoin since I heard about it, I regretted not mining NOT, why I did not buy SHIB and many other things I did not do when I heard about them.
Will I dwell in regret or envy those who did not make these mistakes? The answer is a no, I have to grow up see what I can do with the opportunities I have now because there are still numerous opportunities out there and even buying Bitcoin now is one of them.