The biggest mistake most people make with over-the-board chess:
Waiting too long to get started.
"I'll do it when I'm 100 points higher rated."
You can gain those online rating points, but they won't make you feel any different.
Tournaments aren't where you go to show everyone how good you are. They're where you go to get good.
Ultimately I think the delay is about fear of losing. A lot of people want a shortcut that lets them get good at chess without losing.
There is no shortcut. If you want to become a good chess player, you're going to have to lose a lot.