Yes it's leverage.
They can enter some kind of futures contract, where they only stake their own cash at some high multiple, but they will be stopped out if the price drops.
Or they can borrow some money based on their track record, or by mortgaging their home. This can be very dangerous. Of course some people get lucky.
Personally I feel that if you know what you're doing you should just compound and forget about leverage,︀ but most people I know take the opposite view.