what goes up must come down

What goes up must come down.
1
Anything that has risen or been raised up must eventually fall down.

≅ Высоко летать – больно падать.
≅ Хорошо летаешь, да где-то сядешь.
≅ Хорошо / Звонко поёшь, да где-то сядешь.

Cf.:
go up like a rocket and come down like a stick
{досл.: взлететь как ракета, а упасть как хворостина}, взлететь высоко и больно шлёпнуться {выражение создано Т. Пейном (Th. Paine, 1737-1809)}

And the final event to himself has been that as he rose like a rocket, he fell like a stick. (Th. Paine, "Letter to the Addressers, Referring to Edmund Burke", 1792, HBQ) — Так вышло, что Эдмунд Берк блистательно начал и плачевно кончил.

2
Also used in situations where you want to say that one thing inevitably
follows another. For example, if someone is very annoyed, you know they will calm down eventually.