yes you play only your spare money and lose of course but besides that you can use faucets of casinos btc to just try to multiply and take the cash after no risk of time or investment cash soo you can never lose much just time
In gambling there is no such word called safe so if your thinking it is way to become rich or making good money then do not enter in to this trap. But instead just play these games for fun with some extra money and if your lucky you may win big money or just think it is also like a week end expense and move on with other activities.