Structuring relational database tables
Your first example is considerably better than your second.  It is a standard rule to not use repeating groups of fields and to break fields down to their smallest meaningful value.  BTC_Price and ETH_Price are not broken down to their smallest meaningful value; price and crypto.  In the first example you separated the crypto from price.  This is the correct thing to do.  Joe is also correct in that you should have another table to hold the different kinds of cryptocurrencies with a auto incrementing primary key.  This is often referred to as a lookup table.

Have a look at database normalization and learn about what are called "normal forms".  Your first table conforms with what is called "3rd normal form" and your second table conforms with I believe "2nd normal form".  Typically the higher the normal form the better but 3rd normal form is considered the standard that you should attempt to achieve at minimum.