Hi!
I've been working in the gambling-software dev. industry for 10years, before that involved in softw.dev but other industries. Anybody who promises you to build a site like 1xbet or bet365 is either not having an idea what he's talking about or just tries to get some easy money.
Actually building a bookie website is the easiest part. I assume you're not going for a license. So you need to think about how to move the money around. Crypto only is the easiest. You need a data-feed/odds provider working with a non-licensed bookie. You then need to get the players, traffic - expensive. And a suppor team to handle users, payouts etc. The list goes on and on.
Setting up a bookie from zero is a couple 100k project. So don't even start. Rather look for providers that can get you a bookie/skin with whole infrastructure. I had contacts but this was like ages ago... In short: be smart, don't waste you money like that.