No, no, all it tells you “single white middle class dudes who have too much time to spare for online surveys and consider themselves to be epic guitar players are also X”.
Now, I’d say X and them thinking they’re an epic metal guitar player are both symptoms of something else. And so is their interest in weird online studies.
“Controlling” for cofonding factors on this sample is ridiculous, and doesn’t add any external validity to your study.
TL;DR: weirdos online are weird, but in this example we only picked weirdos who think they’re good at playing guitar. Great study!