Do you let kids win at board game/video games?

When playing board games or video games where there’s a winner do you try to let the kid win? For example, playing a card game do you make moves that isn’t a move that benefits you just to let the kid win, or playing monopoly, purposely spending money to spend all of the money you have? I hope this post is clear but I feel like it doesn’t need much explaining. Does it matter if it’s your own kid, a friends kid, or a kid your watching/babysitting, if you have kids of course. If you do what age do you stop letting the kid win?