I have a question about Game Theory Optimal (GTO) play in poker, specifically for deep stack situations of 100 big blinds (BBs) in cash game situations.
I've noticed that preflop play becomes much more complex in these deep stack scenarios compared to short stack situations (like 5 BBs), where the strategy mainly revolves around push-fold decisions.
My questions are:

In a 100 BB deep cash game, if I'm using the correct push (all-in) and fold frequencies preflop, am I playing an unexploitable strategy?
If so, is the only correct counter-strategy for my opponents to use the appropriate calling and folding ranges against my pushing range?
If this strategy can be exploited, how much EV (Expected Value) do I potentially lose by playing this way?

Any insights or ideas on these questions would be greatly appreciated. Thank you in advance for your help!

You are lsoing ev because with this strategy you are forced to fold a bunch of strong hands that are not strong enough to push 100bb, even hands that are good enough to jam lose ev because your opponent folds a ton to a jam.

Can you give an estimate of how much EV I am losing in this scenario?

Ran a quick 6-max push/fold sim using HRC. UTG 100bb deep, you can only push AA, AK, A5s. Here's your expected value if you shove these hands. Note that even KK loses money shoving. When you shove, you expect to steal the blinds 97.47% of the time.

UTG




Now, compare the EVs with GTO Wizard's (cEV) 100bb solution.

To Haizemberg93's point, even a hand like AA goes from being worth 2.59 to 8.95, a net increase of +636 bb/100.



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SB

SB can open-shove quite a bit wider because there's only one defender ahead of you, but even then you're missing out on a ton of value by playing so tight.

AA goes from 3.51 in the push/fold strategy to 7.86bb in the GTO strategy, a net gain of +435 bb/100.

Considering Exploits

If we force UTG to open wider, something like (JJ+, AQ+), then everyone else can just call one notch tighter (QQ+, AK) and profit.



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MDF

The underlying problem with this strategy, is that there's almost no obligation to defend when you open 100x the pot. You are risking 100bb to win 1.5bb, meaning that with a pure bluff you'd need to be successful 100/101.5 = 98.5% of the time just to break even.

That means that the rest of the field, collectively, only needs to defend 1.5% of the time. If there are 5 defenders, then they share the burden of defense and on average each player only needs to defend 1 - 0.985^(1/5) = 0.3% of their range.

To put that another way, even if every player literally only defends AA, and folds everything else, you still couldn't profitably pure bluff. Now in reality there are strong blocker effects, which is why we saw UTG shoving with A5s earlier, but hopefully you get the point.