Its true that when government come cracking down on bitcoin, people will need another crypto to lay upon that is highly secure and highly decentralized and the one like that is monero which can be rated just after bitcoin in terms of privacy, decentralization and security.
So yes holding monero for long term will surely bring profit as money jumps in it and volume increase by continuous use in dark web.
I agree with you that Monero is great investment, but I can't agree with you that Monero is after Bitcoin in terms of privacy, because, you can easily track Bitcoin transactions on Blockchain explorer.
That's the reason why hackers and criminals using Monero rather than Bitcoin. Monero is untraceable.