There is no 'flow' of money into or out of bitcoin due to futures, and there is no way to arb. Futures is an imaginary betting game. They are completely separate.
Future Contracts Arbitrage 101:
https://blog.bitmex.com/how-to-arbitrage-bitcoin-futures-vs-spot/
https://austeritysucks.com/swapmans-futures-arbitrage-walkthrough.html
If futures at CME/CBOE are traded at a premium, you buy bitcoin on the market at spotprice and short CME/CBOE futures.
The difference minus fees is your arbitrage profit!
With this you also dont run into a total loss --> if btc goes up, the btc you hold is worth more while the future worth less - if btc goes down, the btc you hold is worth less but the future contract worth more.
And there's also no way to arb it on the opposite direction because you cant easily short bitcoin.
Yes i agree to the systemic risks of your first paragraph - so everyone should be clear about them first.
Like you said in an earlier post the futures markets supply is not linked directly to the bitcoin supply - it is linked to the bitcoin price and the amount of $ available to be put into futures.
Arbitrage by going long on futures is difficult indeed, because you would need to short bitcoins - but that too is possible but connected with much bigger risks.
