I don't know about your country, but in Spain if you ever get audited by TAX office for cashing out like 1 mill eur coming from "nowhere" (cryptocurrencies investments) you better have some PROOF of all the transactions ever done from beginning. Using anonymous transactions is cool but it will be better then to keep those "anonymous" coins forever in the dark and never try to cash into banking FIAT or you could even face prison for suspected money laundering. Of course I am only talking about any SUSTANCIAL ammount of money you can't prove how you did earn in the past.
Yeah, it sucks, I hate it.... whatever.... But that's how it is. Again, I don't know about your country and maybe it is different. I am just saying there are reasons, at least for some people, to avoid fully anonymous cryptocurrencies.
P.S.: I do keep old past private keys for wallets/paperwallets/etc I have ever used. It's not that I have a sustantial amount right now... but who knows if it ever will... If it does, I feel more confident if I have the ownership proof from the beginning. Just in case.....
Almost makes it not worth dealing in fiat at all...
The amount of hassle involved using fiat is going to be its downfall. And you shouldn't put into fiat that which you cannot afford to lose anyway. When you only have crypto, all of these problems disappear.
Of course, you need small amounts of fiat for daily life until more people start accepting crypto, but you can easily trade crypto for cash and use that.
YOu can of course use your coins to buy stuff, convert into cash using localbitcoins, etc.... But if you want to buy real state, a luxury car, or anything that is more than 3000 (the legal limit for cash purchases) you need to use BANKING FIAT for that. And for any input into banking you need to pay taxes AND be able to prove its (legit) source.