Sounds perfectly fine to me. Use the times you lose to model losing graciously ("oh, sometimes we win, sometimes we lose, that's okay", "congrats on winning!"; "oh well, maybe i'll win next time!") and don't let him win 100% of the time.

Pretty much all of parenting a 4 year old would involve doing what works. There is no problem here.

What's not to like - these are fun ways to motivate kids. When it is a race to do a chore let him win. When playing a game or something, don't always let him win and teach good sportsmanship.

So far, the best way to make my 4 year old to try new food/do tasks are giving him rewards or compete to see who can do it faster. For example, he does not want to brush teeth, and I will compete with him who can brush teeth first. He does not want to try new food, I will tell him that he can play such toy after trying a bite. He does not want to wake up from bed, I will compete with him who can go to bathroom first. He likes to beat me/win, and I often slow down & most of the time let him win to make him happy. He laughs at me when he wins me. He whines a bit sometimes when I accidentally win.

The best scenarios are that he does all these independently by himself & without me pushing at all. DH does not like this competition & reward system, but it has been working so far. Please share insights if would that backfire when he gets older?