Futures 101

Hi guys, i wanted to understand better the advantages and disadvantages of trading futures on crypto such as bitcoin eth and so on, because i feel like i'm missing something.

For example, the future and spot price are almost the same for btc with maturity 25th march, which for me it is curious because btc is a very volatile asset and could be more than possible to break the futures price (of course also the opposite reasoning).

Also, i dont understand why i hear people telling that it is better to trade futures instead of holding them till maturity. Can someone also explain me this?