These days we can get more bonus based on the amount being wagered, but there isn't no free money to play and get real money out of the same. Few sites provide free money, but those are very little and can be renewed once that were empty. Apart from this sites have got tokens that are a way to experiment the game and that doesn't pay real money.
Any site is interested in the fact that you would deposit your real money, otherwise it will cease to exist. Freerolls could not be too large if they did not lead to an increase in the number of players as a result.
After all, as a rule, most of all freerolls are loved by those who do not have money for their own deposit. Therefore, it is more profitable to issue tickets for freerolls in the form of a deposit bonus.