But, what if Bitcoin never reaches a new ATH? Then, I'm afraid that most people "hodling" Bitcoin will lose all of their investment in the long run.
What are your thoughts?

No new ATH would mean not much further evolving of Bitcoin - as technology and as acceptance/use too. It would mean Bitcoin dying. It would make the miners leave. It would be bad.
But I don't think that this can realistically happen.
Also, how many years means "never"?!

Bitcoin is simply too good to stop being adopted and used by people all over the world, as the political situation all over the world begins to worsen and their economies worsen as well we will begin to see people looking for alternatives to what the government offers and bitcoin will be there for them, also people are not going to go against what it is on their best interest if they have a neighbour that became rich because he invested in cryptocurrencies you can be sure they will try their luck with cryptocurrencies as well.