100% welcome bonus is a tempting thing, just imagine you make a $100 deposit and get a bonus almost worth that much, bonuses and events are marketing tricks that no gambling site should miss and this site realizes that.
If you intend to claim this bonus it would be better to read carefully the bonus rules, how many times the wagering requirement must be made by the player before finally the winning value can enter the main balance and can be withdrawn, reading the rules is important so you don't feel trapped later, marketing is the casino's way of introducing their site and attracting players.