A well-known and insured exchange is by far the safest way to keep your Bitcoin. These large companies are extremely secure, and they are insured if they get hacked, so you will never lose money no matter what.
It will only be described as the safest until your funds gets frozen by the exchange for either receiving payment from a taint address or doing any other thing that violate the casino's terms and conditions, thats when you will know that this safest you are calling it as the bet place to save your Bitcoin will automatically change. Because for the fact that ColdCard Bitcoin hardware wallet was compromised, that doesn't mean that the rest hardware wallet aren't safe anymore. And for the fact that it grants you full control over the protection of your assets, that makes it the best.
I've spent
decades with money in a bank--basically I've had money in a bank since I was 12 years old. Everybody I know is about the same, and between friends, family, coworkers and acquaintances, that would be thousands of people over the years. I also listen to the news, including the local news.
I've never--EVER--heard of anybody losing their money using a reputable financial institution and an insured account. It just. doesn't. happen.
Of course, I don't tend to consort with
criminals, so there's that

. And I live in the USA, so here there has always been a stable financial system (and if it becomes unstable the price of BTC will drop by 99% as consumer investors sell their risk assets including their Bitcoin, so then it wouldn't matter).
I get that there are a lot of people who live in unstable countries or are...
actual criminals who need to hide their money. But for the other 99.9% of the population, self-custody is extremely dangerous compared to the safety of storing something in your name guarded by professionals far away from you, and insured even if they lose it.