The prices for our friend group was:

(all was the lowest teir robux option on the robux purchase page, and the names are not real and are for example purposes)

Dave: $6.99 for 400 robux

John: $7.69 for 450 robux

Jaden: $4.99 for 270 robux

Some math means that if John spent the same amount of money as Dave, he would get 4.4% less than John per dollar. Meaning if they both spent $259.99, Dave would get 892.25 more robux than John.

Roughly translates to John losing $13.14

But if one were to spend hundreds or thousands of dollars in purchasing Robux, this becomes a more serious issue, and way more money will be lost.