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I don't see any reason why you should regret, or let it stick really. You can regret, yeah, I won't deny that. Just don't let it linger, it has absolutely no use in your life. It doesn't turn back time so why bother letting it stick around. And no, even if Doge did make me regret (which it didn't), I still wouldn't try to find the "next" Doge. I'd still use my own standards in trying to judge a project. That's what I did with Bitcoin, that's what I'd do with the rest of my big investments.
I can spare a few bucks shit coins though for a little bit of gamble here and there

.
Just for funsies - it's viable.
And I agree with your points about remorse and regret - OP, just let it go.
Find something worth elsewhere and move on.
Everything will be better from that experience on.