This thought experiment is not about solipsism. If you would like to have that discussion, go argue with some other people you’re imagining.
Presume that, despite your impressions to the contrary, you are a brain in a vat or a Matrix-style pod dweller or a software program.
How does it make sense to talk about you? What ways of describing you relate to something which does exist?
A few I can think of:
It seems like it makes sense to talk about your past and your future. How the other existing aspects of you have changed or will change refers to something real.
What you value or dis-value, your emotions and preferences also makes sense to talk about.
Your perceptions and theories of what you perceive may not refer to anything which exists but you perceptions/theories themselves do exist, much like a drawing of a dragon exists even though the dragon doesn’t.
Does this presume that I have learned that I’m a brain in a bottle, or a sim, or an AI, or whatnot? If I haven’t, and I’m still under the impression/illusion that I’m still a human being in a hot apartment typing philosophy on the internet, then I’d talk about myself the way I always have…
But now that I know I’m a sim, I would still pretty much talk about myself as usual. Why should I have to add extra verbiage? “It’s hot today” is still true for me, even if I really should say, “The simulated environment is hot today.” “I’m depressed” is still true; I don’t need to add, “My simulated emotional status is being manipulated to make me feel depressed.”
I’d continue to use “shorthand” conversational modes, in all but the most technical conversations. It’s hot, I’m thirsty, the Chargers suck, etc.