Crypto (esp BTC) is a well defined zero or negative sum game. How do you propose /most/ people make a profit?

I didn't propose that. I just linked a relevant indicator. If you'd like me to predict the future, I predict that eventually BTC will fill a similar niche as gold - it will outperform cash under the mattress, but underperform index funds. You'll be able to spot the transition when the MVRV starts to center around 1.0 instead of its current ~1.5. But I couldn't begin to guess when that will happen. Maybe this crash is the catalyst, or maybe it will happen a decade from now. ¯\_(ツ)_/¯

Please elaborate, how is it a negative sum game?

For every person taking money out someone else has to put money in (which would be zero-sum) plus the miners taking their cut.

By that definition, which financial instruments aren't negative sum? E.g. stocks trade hands in a very similar way, and companies can always issue new shares.

Company sells stock.

The money builds a new factory. Or in the case of Google, a data center, or other such item that allows the company to make more money.

Later, when the company is worth more, the shareholder sells the stock back and/or gets a dividend (aka, a slice of the profits).

Everyone wins.

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In contrast, the BTC you bought was likely made using stolen electricity. So we're already negative sum to the start.

The same thing could happen with crypto. A smart contract developer sells crypto to fund development of a smart contract. That smart contract can provide new utility and drive demand for the currency.