Because all exchange platform need to the personal info.
You can buy it on major exchanges like binance or Kucoin. KYC is not mandatory for binance users, if you are not KYC you can still withdraw money daily without any problems.
Also I can't buy huge amount bitcoin and altcoins via the platforms.
I think binance and Kucoin or most of the exchanges can meet the number of altcoins and bitcoins you need to buy.