Warren's just following his old philosophy when many are still euphoric after Trump's winner in US election, then he took advantage to sell his asset at peak.
Honestly, now is the wrong time to buy Bitcoin. Anyone who is buying now should've bought a month ago.
Although, if you are looking to sell off some of your holdings to get some cash, now is a good time. I just sold about $500 worth of BTC. Zero regrets whatsoever. (And I still have a huge stash.)
In reality, buying bitcoin at this point will depend on the individual because not everyone has the opportunity to enter the market as early as we do. Many people have only heard about bitcoin in the last few weeks, how can they buy bitcoin from a month or more ago? If they don't buy now, when is the right time to buy and what guarantees that the price of bitcoin will drop to $70k or $50k for them to buy? At current prices, this is not a perfect time to buy bitcoin for long-term investors but for newbies, it is completely different. So, it depends on each person's decision.
But I also won't give investment advice to anyone at this point but I won't stop them if they want to invest.