3. There was enough liquidity at the peak of bullrun so it was possible to convert ONION to BTC and then to USD or maybe some part even directly to USD.
That was not possible. The maximum volume was 3.20 million on January 09, 2018. I don't think there was enough liquidity at that moment to dump 150000 ONION (@$20). It would destroy the market without any doubt.
However, listing on some bigger exchanges was definitely possible back then but now we are left none.
I see higher volume on 10th January 2018 above 4 million on CMC, but that's not so important. Of course, it was not possible to dump whole amount during one day, it would not be a good idea even with higher volume. But it was possible to sell smaller amounts during the peak of price and volume which lasted around one week. Even with average price of around 15 USD per ONION, still would be a great deal.
Of course, it's easy to say this now, when we have all these past data. And I'm also not saying that listing fee of 3 million USD is acceptable regardless of ONION price. Therefore I questioned it, I'm pretty sure that there were cheaper options.
But most important is the general logic here. When the project has all funds in highly volatile ONION, it is not a wise decision in terms of risk management and project financing. There is a short peak with high value and then long time with very low value preventing any serious spending on development, marketing, listing, etc.