There's this guy in crypto that you hear about early in your journey: The bagholder.
He is a man who did the opposite of everything you've been thought to do..or should do.
He bought high!
He bought for the wrong reasons!
He never sold...
But what makes a bagholder a real bagholder is his endless belief in the fact the everything will turn around in his favor..eventually. He'll say stuff like
"The fundamentals are tight!!"
"GREAT TEAM!"
"vision!!!"
He'll try to convince you to buy, believe and ultimately transform into himself.Nothing makes a bagholder happier than seeing another fellow bagholder ( unless it's a different bag he's holding in which case..watch out :D ).

Here's a little story of how a bagholder becomes one. Might be not the only origin story.
In fairness, some bagholder are true believers and some are already rich ( Ripple bagholders, ETH bagholders...). But here's the one you will encounter:
He thinks he is a trader.
Trading is so easy. I will buy this now, sell at 2x. Repeat 100 times. Be rich.
Easy.
So he buys. It goes up a bit. SO EASY!!! He won't sell, 10-20% profit in one day is not enough for this guy, he feels it will go higher. Oh yeah, Bulls and stuff. UP!
Then...it goes inevitably down. Not only because usually what goes up must come down but also because he picked a shitcoin. In this case, it's a coin called "guppy". I mean, even the name is moronic.
You know what guppy is? Is the coin of a site that wants to be "Tinder on the blockchain...with a social side". PFFF! sound more like a pimpender on the blockchain. Ripe for a pump and dump and done.
Our guy bought on the pump. He forgot to sell on the dump.
So.
What does he do?

Sells lower on panic. Buys back on the pullback. Does not sell when it goes to die. Buy some more down because he heard that's what "traders" do.
Accepts his faith.
Transforms into this new person who just loves "guppy".
He is in the gilde now. A bagholder.
The legend says, he still waits for the pump.
If you see him, just go the other way.