All my friends who got into the crypto game by altcoins, also own Bitcoin. No exception. So the 'altcoin retail' is definitely a factor for BTC's liquidity as well. Besides that, liquidity providers do their part, and don't forget institutional entities are also getting more and more into asset classes like lending, for example, using both DeFi and CeFi. "The lack of liquidity also creates arbitrage opportunities, for example, if different crypto exchanges have different liquidity levels. Crypto lending provides liquidity to institutional investors such as hedge funds, crypto exchanges, or market makers, allowing them to exploit these arbitrage opportunities." (source
https://www.cryptostudio.com/lending-abc/market/) so it's definitely interesting to see how official/gov entities and institutional investors are adapting in the next weeks and months, for sure, combined with all the retail acceptance...