Time
What is the most painful type of loss ever?

Early in my chess journey, I mated a guy while down a queen by sacrificing a rook (not that I had a choice; it was forked alongside the king) to threaten checkmate with my king and other rook. My opponent accepted the "sacrifice" with zero hesitation; and so, he lost by checkmate, despite being up ten points of material and having numerous other positional advantages.
If anyone ever makes an argument for triple exclamation mark "???" moves being a thing, I'll gladly show them that as an example of why they should exist. I could feel my opponent dying inside when I played the checkmating move, as hilarious as it was. I know I would definitely die inside, watching the evaluation bar instantly go from +8 to -M1
I also had another one where I sacrificed a rook in a similar manner (down a queen), only the sacrifice wasn't forced. I just quietly set up my bishops and other rook to create the checkmate threat (and unlike the last one, it was actually fairly subtle), and just like the other guy, my opponent took the "free" rook with zero hesitation. And then they got checkmated while being up by an entire queen.
It's funny when you do it to others. It's disheartening when it happens to you. But in both cases, it was entirely their fault for not paying attention.

The 1st, then 3rd then 2nd. to be honest, I dont even feel bad if I get reduced to rubble slowly, because I know I got outplayed. So gg to that is what I think

Personally I really hate it when I’m in a winning position but then an Eldritch horror manifests over Earth and initiates the apocalypse. So annoying

There's no resigning in blitz/bullet where your opponent can easily lose on time despite being way up in material or position, but...
Resigning can make sense in daily, or slow live games. Most painful would be to resign with lots of time left because you think that you're losing, but then seeing that you actually had a winning tactic.
So what is the most painful type of loss ever?Is it getting flagged in a totally winning position where you are up by 6 pawns and a rook?Or is it getting slowly reduced to rubble by the opponent's domination of 6 queens?Or is it getting mated when you're up a queen?