eat one`s cake and have it too

To wish to have one's cake and eat it too or simply have one's cake and eat it (sometimes eat one's cake and have it too) is to want more than one can handle or deserve, or to try to have two incompatible things. This is a popular English idiomatic proverb, or figure of speech.The phrase's earliest recording is from 1546 as "wolde you bothe eate your cake, and have your cake?" (John Heywood's 'A dialogue Conteinyng the Nomber in Effect of All the Prouerbes in the Englishe Tongue') alluding to the impossibility of eating your cake and still having it afterwards; the modern version (where the clauses are reversed) is a corruption which was first signalled in 1812.
See more at Wikipedia.org...

use or spend something and still keep it He always wants to eat his cake and have it too and is never prepared to sacrifice anything.

idm. สนุกกับการทำสองสิ่งไปพร้อมกัน, ใช้ทั้งสองวิธี

enjoying both having sth and using it up