There are SPX options that expire in 2027, 2028, and 2029, those seem more attractive to me than 2-3-y-dated VTI options, especially given that they have strike prices that are much further out of the money.
Would you mind posting the specific contracts you bought?
Implied volatility of long-dated, far-OTM calls is similar between AI-exposed indices (e.g. SMH) and individual stocks like TSM or MSFT (though not NVDA).
The more concentrated exposure you get from AI companies or AI-exposed indices compared to VTI is likely worth it, unless you expect that short-timelines slow AI takeoff will involve significant acceleration of the broader economy (not just tech giants), which I think is not highly plausible.