Crypto or cryptocurrency includes Bitcoin and alternative cryptocurrencies aka. altcoins with market for investors and traders to do their jobs.
They can invest directly by purchasing those cryptocurrencies or indirectly through Spot ETFs. It's their personal choices and need to research on risk of trusting third party entities to secure their money. If they afford the risk with third parties, they can go with Spot ETFs. If you can not afford that risk, go with non custodial wallets, be their self custodians to secure own money. Be their own banks, with non custodial wallets that better, need to be open source, not close source.
Choose wallets through research, read reviews, reproducible tests, and have proper, safe backups.
Reminder: do not keep your money in online accounts or in other words, "Not your private keys, not your coins".
How to back up seed phraseChoose your walletsWalletscrutiny.com. Reproducible tests.
Of course. It's all a matter of personal preference. Those who want the flexibility of not having to protect their Bitcoin or set up a wallet, would find investing in a spot ETF the best choice. Others will simply choose to invest in BTC directly and store their holdings in a non-custodial wallet for safekeeping. This last method gives you full control over your BTC. As much as I don't like institutional investment firms buying up all of the BTC, there's nothing we can do if we want mainstream adoption to rise over time.
I wouldn't say Bitcoin's future is in doubt, especially when demand for the cryptocurrency is higher than ever. Perhaps, altcoins' future is in doubt. Not Ethereum, nor Solana. But low cap altcoins and "meme" coins that are purely-speculative. The crypto market behaves in many strange and bizarre ways, so expect the unexpected.