RE: personally stored keys are less secure ...this is very subjective. You don't "hand" your wallet keys to an exchange: you don't even have them. Meaning "your" CC is a lot like "your" USD in a bank: subject to taxes, send restrictions, asset freezes, IRS audits, and a whole host of other unnecessary and inconvenient crap. Being taxed on CC gains relative to the USD is ultimate hypocrisy. It's like being taxed on swiss francs or yen you hold if the exchange rate changes... except instead of an unlimited write-off for losses like traditional forex, the cap is $3000 to form a one-way YoY tax valve.
Literally nothing about the government's stance on or (severe lack of) understanding of cryptocurrencies makes any sense other than it definitely reminds me of good ole' Reagan: "If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it."
RE: if something happens to you ...that is an excellent point. You wouldn't get this without an exchange, yeah. If subjecting yourself to all of the above to reap this benefit is worth it to you, that's a favorable tradeoff to make and one you definitely should.