Bitcoin is not a currency. It's a speculative artificial commodity, worse than beanie babies or tulip bulbs. It's also literally burning electricity to solve useless computational problems to get your virtual widgets. Current estimate is each bitcoin is roughly 74 terawatts of power. Bitcoin alone uses more power than Argentina, according to recent estimates. This power usage will only increase for Bitcoin, for mining/validation totals.
And of course rich assholes want people to get suckered in to the Bitcoin pyramid scheme now, when they control large portions of the available coins. Lost coins as mentioned still count AGAINST latecomers, or if they are ever recovered/found later, you're just making some asshole a multi-billionaire overnight.
It's also, as mentioned here, TOO FUCKING SLOW to be used as a currency. All other cryptocoins will have the same speed problem, or they will be insecure. cryptocurrency as a whole has this computational issue, that will most likely never be physically solvable. A side issue that also can't be ignored, is Bitcoin and other cryptocoins are vulnerable in theory to 51%+ computational man in the middle style attacks, where whoever controls 51% of the validation computations controls the blockchain. This probably won't ever happen for Bitcoin itself, but up and coming coins will most definitely be controlled before they even get to you. As it is, Bitcoin is already controlled via old methods of market manipulation, similar to gold/silver prices. Scammers like Elon Musk will tweet-control Bitcoin's value for years, now that he has some to throw around. New adopters will never make the kind of money old adopters or large scale wealthy holders will have, you will always be feeding them your money.
A simple test for any crytpocoin, when people talk about it, do they talk about it's worth in $USD or Euros, aka a real currency? This is how even a layman can see that these are not usable currency, just a stepping stone for manipulation before it gets to an actual fiat currency. The fact that banks are stepping in to start abusing bitcoin should at least trigger most peoples' apprehension and suspicion, but personal greed will probably win out.
*EDIT* word choiceThis comment was edited on Feb 13, 2021, 21:22.