Winning big sums of money at online casinos is indeed possible, but it's important to understand the odds and the nature of casino games. Here's how such wins occur and their frequency: High Variance Games: Big wins often come from playing high variance games like slots, where payouts are infrequent but can be large.
Generally speaking, you'll find better odds at an online casino because they have smaller overheads. They don't have rent to pay, they have fewer staff members, etc. So, you'll find that many classic casino table games, including blackjack, tend to have a lower house edge in an online casino.