how are you going to carry all that cash around? Let's assume you withdraw even $50,000. It will have to be declared when you leave the country.
If we think about 50.000 euros, it means 100 banknotes in denomination of of 500 euros. And yes, this amount should be declared when leaving the country. But if we only think about how to carry this amount, it's not too difficult to carry 100 banknotes, is it? They can easily fit inside a pocket.
My point was that you will most likely be questioned by authorities on the source of those funds and you'd have to admit that they were cashed out from cryptocurrency holdings or risk an arrest, or seizure of those funds.
Admitting that will of course lead to even more questions on where did you obtain the crypto from, since police deal with a ton of scammers that have a
modulus operandi like that.
The distribution of 500 has stopped, but even if it hadn't, spending such a large amount is almost impossible. I remember having trouble even at the gas station, which handles quite a lot of money daily. Smaller notes, such as 50 or 100 ones, would be more preferable. Bringing a ton of cash through the airport is impossible without going through customs declaration; that's why GazetaBitcoin mentioned splitting the money into a few trips. On the other hand, having a decent amount of undeclared cash doesn't help at all, because you can't actually use them for large cash purchases.
Why do you think you will be questioned if you'll have this cash in your wallet? We're not talking about a suitcase full of money like they show it in movies, but a bunch of 500EUR banknotes in your wallet. Besides, you can rent a car and drive home and avoid all these security checks, customs etc.
Believe me, spending 500EUR banknotes is the smallest issue you're going to face. There are so many ways to exchange it to smaller banknotes including deposit ATMs, bank branches etc.
Large cash purchases is also not a problem. There are sellers and companies ready to do everything to make some profit. You can buy a $100k car with cash for example without an issue. The dealer will think of a way to do this. You certainly need to do research in which countries it's possible, in some countries you can get in trouble!

Not really. I used to work at a gas station, and we generally avoided accepting 500 bills. Their distribution has stopped, and in order to exchange them for smaller bills at a bank, you have to declare how you acquired them and actually have a bank account with them; thus, your identity is somewhat given away. Moreover, as LoyceV already mentioned, the car needs to be registered and have its value declared. No new car dealership is going to declare it for a few thousand euros when there's documentation that they've bought it for way more.
Generally, everyone has the right to refuse to accept such a large bill, and as I've already mentioned, we usually didn't have the necessary change to return.