I'm sure SwC has also prepared promotional or marketing campaigns as well as several other ways to gain more loyal and new customers.
Regarding budgetary funds in carrying out promotions or marketing, they must already have it and everything has been prepared.
They already have a casino that has been running successfully until now so income in their business or profits can be obtained, moreover, the owner of this casino must also have a lot of money that can be used at any time to carry out a development or other things that can make a casino they are advancing rapidly.
In fact, I do not really agree with using jackpot funds to be used for casino marketing because the existence of a large jackpot fund can also be one of the factors that can attract gamblers to use SwC with the aim of chasing the jackpot.
You are making assumptions on them having loads of money, which could be true or not, whereas I have pointed out one of the option to obtain more marketing funds.
You also make assumptions on owner having lots of money - even if that's the case, the goal of sustainable business is to make money for itself, i.e. marketing pool should be built up from profit from operations.
So what if the jackpot is huge if no one had won it in years. If something seems impossible to achieve, it loses its appeal. They could slash it in half and it'll still be huge. And they could use that money to increase activity, and, in turn making jackpot pool growing at a higher rate.