I’ve came across a couple no deposit bonuses too and yep they’re real but not as simple as they sound, Most of them have tight terms like high wagering requirements or max cashout limits. So while you don’t pay upfront, you frequently wind up needing to deposit later if you want to withdraw anything t’s helpful for trying out a site but not something to entirely rely on.
You are right mate, it's not easy as it sounds because after receiving the free bonus you might not be able to withdraw it because it's free. In this case, you shouldn't take it serious because those are traps, some are used to get customers nothing more.