Yes. Casinos welcome all types of gamblers to their sites, whether they are high rollers or casual players. The two groups are essentially the same, with the only difference being their strategies. High rollers tend to wager in hundred, even thousands of dollars, whereas casual players just want to go with smaller notes.
In fact, casinos love high rollers because they are the most profitable customer group. One visit from the high roller is enough to offset the cost of dozens of other casual players. Nevertheless, as mentioned above, all gamblers are welcome at every online casino for real money.