Re analysing in poker. Do you HAVE to be in position?

Let's say I have 99 in the big blind. Let's say idildur in on the button in a cash game and he makes it 3x. Small blind folds. Against isildur range I feel I'm justified to 3 bet. So I do to 4x his raise. He 5 bets me 2.5x. Now isildur is known for being crazy. So I feel he can literally have any hand at all. However the thing is, with this thinking that means I'd happily 5 bet with q10 just presuming he's bluffing, because he's isildur. But he's representing a hand that against a normal player I'd have to fold my hand. Let's say also it's impossible to read him. Should I just fold? Or is it justified to 5 bet? Or is it even justified to call? I'm out position so does that take smooth calling out of the equation? Oh btw I don't have enough to make hitting a set justifiable. Btw that this exact same hand however I'm in his position, would I bet justified to call a 6 bet about 4x in position with 99?

And my main question is do I HAVE to have a read if some sort to make a move against a player who is obviously ultra aggressiv?

If you believe a player is "obviously aggressive" that would constitute a read on your part.

Isildur will destroy you if you call or 3bet. I'd just fold Actually, it's probably best to move table

If you called or re-raised too much he would just adjust to it and change his ranges.

Stacking 99 pre against Isildur1 is totally standard.

Big part of the equation missing here > 'our Image'

If we 3b a merged range isn't it pretty easy for Isildur to adjust and play almost perfectly against us?

This

THIS ALWAYS HAPPENS TO ME! gawd they just get so lucky, but at least we're playing 20k plo.

I was also playing a pick-up game w/ lebron ealier this week, he just kept getting so lucky

I'm not 100% sure what you mean by this.
Can someone elaborate more?

A merged range is a wider value range that includes hands like 99, AQ. A polarized range would be nuts (QQ+/AK) and bluffs.

I think I understood that part. I just don't understand is the hero 3b a merged range, or he has a merged range? And how will Isildur be able to play almost perfectly?
Those were my confusions.

Hero's range is merged.

If Isildur1 realizes that Hero is 3-betting a merged range with no bluffs, he can obviously drop his bluffs and continue with hands that do well against our range.

(I don't think Isildur1 is really ever tightening his stackoff range so that 99 is totally crushed in a BTN vs. BB situation but that's another story).

a deep stacked game is made for agressive players like Tom Dwan. If you don't have a very good read you will loose your total stack.