How does this fit together with a startup? Would investors happily invest into this knowing not to expect anything in return for at least the next 5-10 years?
Oh, you mean like OpenAI, Anthropic, Gemini, and xAI? None of them are profitable.
Anyway, how much that matters for an investor is hard to form a clear answer to - investors are after all not directly looking for profitability as such, but for valuation growth. The two are linked but not the same -- any investor in OpenAI today probably also places themselves into a game of chance, betting on OpenAI making more breakthroughs and increasing the cash flow even more -- not just becoming profitable at the same rate of cash flow. So there's still some of the same risk baked into this investment.
But with a new startup like LeCun's is going to be, it's 100% on the risk side and 0% on the optionality side. The path to profitability for a startup would be something like 1) a breakthrough is made 2) that breakthrough is utilized in a way that generates cash flow 3) the company becomes profitable (and at this point hopefully the valuation is good.)
There's a lot of things that can go wrong at every step here (aside from the obvious), including e.g. making a breakthrough that doesn't represent a defensible mote for your startup, failing to build the structure of the business necessary to generate cashflow, ... OpenAI et al already have a lot of that behind them, and while that doesn't mean that they don't face upcoming risks and challenges, the huge amount of cashflow they have available helps them overcome these issues far more easily than a startup, which will stop solving problems if you stop feeding money into it.
Talk is cheap. Until they're actually cash flow positive, I'll believe it when I see it