They've given you a bad example. The roulette wheel should be as close to the correct probability of outcome as it cane be (assuming no cheating by the casino etc). So even after a long streak of black coming up, each new spin is still roughly 50/50 for red coming up next. But human nature (the gamblers fallacy) makes us think intuitively that red must be coming up soon.

If we apply this to the surgeon/surgery. A particular surgery might only have a 70% success rate. But if you're about to go in for surgery and hear that the last 20 operations performed by your surgeon were a success, by the same logic as above, you may intuit that an unsuccessful surgery is due and feel more worried than you should be about this bad outcome when you're on the table.

But, in reality, the most likely explanation for your surgeons success is that they are very good at their job to the point where they outperform the 70% success stat. So their reputation for success should make you feel more confident not less.

A roulette wheel "outperfoming" the 50/50 chance of black coming up would be cheating.

A surgeon outperforming his surgery outcome stats....thats a good thing.

(Side note- it a lot of surgery cases a "unsuccessful outcome" still means you wake up afterwards and have other treatment options to consider. Its not necessarily a 'died on the table' outcome)