They can afford to loss because it's not their money. In a traditional casino the steamers are giving credit balance to play with certain conditions. Conditions like to wager x amount and anything after the wager requirements, it's the streamers money. The amount is so high that most of the time the steamer does not make it. There are other conditions like play until you lose the entire balance.

These streamers are paid for their time just like an employee. So it does not matter if they win or lose.

I think it's not applicable for an employee and they can justify it by saying the streamer is paid for his job.