Bitcoin was created by an anonymous individual going by the fake name Satoshi Nakamoto. If you read Satoshi Nakamoto's white paper, link here, you can get a good understanding of bitcoin, the largest crypto by far:
One of the things Satoshi mentions, which currently and will forever hold true for BTC, is that an attacker with 51% of the hash rate (CPU power) of the network can control the network. Bitcoin, a "decentralized" currency, is not actually decentralized. The vast majority of the hash rate is in china.
As of last year at this time, the chinese controlled 65% of the CPU power vs just 7% for the united states. The reality? It is centralized in China since they have well over the amount of CPU needed to take control of the network and do they as they please with the blockchain. IMO Bogleheads interested in purchasing BTC need to understand that they are purchasing an asset under the control of the Chinese communist party, not a "decentralized" currency, and the risks that come along with holding an asset controlled by the second most controlling government on the planet. Jack Ma should be a good lesson to anyone interested in having their assets in China.
Any of the other "decentralized" currencies that use proof of work can also be controlled by a 51% attack. If you have the CPU power for 51% of the btc network, the largest network, you have the CPU power to control the other "decentralized" currencies. Their network is smaller, less hash rate, easier to have 51%. I think bogleheads can see what I'm getting at here.
Ethereum, about to transition to proof of stake, will be a good bit safer.