This issue is common with young kids, and it's understandable. They prefer doing things right away instead of just waiting. I once read that little kids can't really think about the future. So, when parents say they have to wait until tomorrow, the kids get upset because to them, tomorrow seems really far away. I think this inability to understand time might be why waiting is hard for them, which makes sense.
若い子供たちにはこの問題がよく見られ、理解できます。待つ代わりにすぐに物事をしたがる傾向があります。かつて子供たちは将来を考えることができないと読んだことがあります。だから、親が明日まで待たないといけないと言うと、子供たちは明日がとても遠いと感じて怒ります。時間を理解できないことが待つのが難しい理由なのではないかと思います。