what is the point of testnet coins here? testnet is moslty to test the new dev of the main network just like bitcoin main network with zero economic value.
You can give the user any amount as it is an update of the database and after he succeeds in successfully trying the platform, that balance can be replaced with your free tokens.

Personally, I do not encourage the use of leverage and risky trading like that, as even repetition and practice will not make you a professional.