It depends on your game and what you use your PC for.
If you’re a casual gamer who isn’t trying to become a Fortnite champion or doesn’t mind playing games on less than the best resolution, I don’t see why not. However, the Steam Deck is a handheld. If you regularly game at your desk and are comfortable there - I wouldn’t see the Steam Deck as a replacement to that, but rather as an addition.
If you have a mid-tier PC and have a secondary console for your more serious gaming sessions, there is no reason you couldn’t do the majority of your gaming on a Steam Deck. You will have to come to that decision on your own.