There's no guarantee that they can keep it as hackers are also present around, it's not safe so better to stay away if possible.
It's a risk that you'll going to take when dealing online, think twice before taking your step.
Much better to read all the house rules and understand everything.
From all of that, we need to be careful if the gambling site give the welcome offers, but they require KYC. As the name, welcome bonus, is the way to attract people to come, but we don't have to think about getting a big welcome bonus because that will not always come to us.