Hey chill down, we don't know if they are selling, there is no proof.
Maybe they just setup their new infrastructure for the beta release and they moved the money into that infrastructure.
The system will give out AMP to curators I think so they need to fill up the bucket from where it will be given out, maybe that is where the AMP went.
No 100% proof but high chances are they are selling:
* Exactly 1,500,000 AMPs have left
Founder Reward Wallet* 947k AMPs reached an
address that starts with "1Po1o", has 100+ mil USDT and 25 mil AMP. I bet it is Poloniex.
* 300k AMPs reached an
address that has 47 mil USDT and 12 mil AMP. Either Bittrex or second Poloniex address.
I'm pretty sure this is not related to infrastructure

Besides, there are other wallets to "give out" AMPs like "User Reward Wallet" and "Content Creator Wallet".
What I don't understand is why touch Founder AMPs at all when they have raised like 4 mil USD.