Starting a casino will always be expensive, regardless of how you set yours up. As previously mentioned, cash-on-hand requirements alone will often be more than $20 million. You will also need to buy equipment, land, build your casino, and purchase a gambling license, all of which can be very expensive.
Just as land-based casinos must be regulated, so do their online counterparts. In order for an operator to offer games of chance, such as video slots, table games, or sports betting, legally, they must have a license that covers the territories they want to offer the games.