...the lesson I've learnt is if I have to do invest in such projects the team must not be anonymous.
Bitcoin's founder was and remains anonymous. But that's because the idea and protocol is so good, we don't need to know the name of the creator. An anonymous team or an individual doesn't necessarily mean the project is bad and is a scam. Unfortunately, many are today because they are centralized, pre-mined, and tokens created from thin air meant to enrich those who minted them.
And this is why new projects dev are escaping arrests when they scammed their investors, anonymity has been used in so many fraudulent ways and nothing was done about it, just because BTC Dev remain anonymous and the project works as intended doesn't mean others have same aim as Nakamoto.