All answers above are wrong.
Cryptocurrency projects uses .io or .info or .tech or .shit or whatever simple because .com is not available or it is more expensive.
Take for example.blockchain.info. they bought .com finally after 10 years, for millions
About that price, .IO is more expensive than .COM.
This information is wrong and makes absolutely no sense.
I agree with Bitmover here.
Price is the main reason.
As we all know that Roger purchased Bitcoin
.com for himself
he can now manipulate with many newcomers and BCH Bcash.
In the end... if search engines detect your website, it does not matter so much what domain they used .com or .io
or maybe new blockchain based .ZIL domains