It looks like you have had luck with the altcoin you bought, maybe you can provide information on an altcoin that is suitable for buying again and has the potential to increase the price perhaps more than x10 again.
At most times, these kind of purchases of altcoins won't give you that much gain in the short term. And that's why as you've said, he's a lucky guy if he had gained 10x from his investment after listing on an exchange. Not all listing are like that when it's come to ROI. So, a memecoin in short term and 10x already was a great deal for him if it's a real thing that he'd gained from buying too early. Because normally, upon listing there's always a great dump waiting ahead.
It is true that upon listing, most coin gets dumped by investors and other holders so as to quickly recover their investment. I have come to realise that early adopters of a project are always at profit because it is either they get their coin or token free by just performing a little task or they buy at cheaper rate so as to aid the project in progress.
After listing, most coin or price value drops drastically and of the project is not a good utility project, that is the end of it but if It is, there would definitely be a price manipulation so that investors could get more of the token while the weak hands sells off. After they had succeeded in manipulating the market, they sell high to gain more since they are very sure of the project they invested in.