Certainly no casino site will invest this entire amount in a single day.
It takes good analytics and marketing tools to choose the right channels at the right times.
Some platform will give more return to the site on weekends, another in festive seasons or else in some quick promotion that the site wants to promote, but they will never happen simultaneously all on the same day in the proportion you estimated.
However, still the values should be astronomical. However, I believe that the return pays off and the profits are greater than what is invested in marketing.
That's a huge amount, even for a casino that's been in operation for so many years. Casinos will prioritize their plans first and market them according to the plans they have drawn up. They may use one or two social media to promote their casino site so that the funds will not be too large and only run out for promotion costs. Casinos also need to consider other things, such as maintenance costs, employee salaries, etc., so sticking with the plan will be better for the casino. And even though the profits may also be greater, the casinos already have the calculations, so they won't be too eager to chase the profits. Casinos believe that one day, their business can grow even bigger.