I've been wanting to make another one of these :)
My Prefix is an abbreviation of the whole word
Which consists of just a few letters
My Infix can be many things
But it is also an abbreviation for 3 different words
My Suffix is something that you may find on the streets (If you're lucky)
But of course, you need to add a letter to it before that happens
To clarify :
What I meant by the forth line (Abbreviation of 3 different words) is like, for example, STR for Strength, String, Strung --> Just pretend that those are correct. The abbreviations has to be correct, though, for the riddle :D
Hint :
The word is something everyone will always gain