6 refueling flights is pure and utter copium for HLS. Even 10 would be a stretch. It would have to outperform in every metric. This is for a mission which is suppose to happen in 2028, hell the uncrewed test mission was suppose to happen last year. However 10 flights plus one for tanker/depot and one for HLS is 12 flights total for a single disposable mission. That is a ton.
Sure you can brute force your way through it as a one off every couple years for NASA at a cost of $3B to $4B each (...)
It sounds like you're budgeting for everything to be sent to the scrap yard afterwards. The F9 booster lifespan leader is currently at 32 launches, I doubt they're targeting less for the SH booster. Sure, for cadence reasons they'll need more than one but for lifetime cost one HLS would consume 1/3rd of the lifespan of one booster.
The second stage is the cost joker, but seeing as they've managed to soft land now a number of times I image they'll do better than nothing. Once they start launching Starlink satellites on Starship they'll be working towards that every launch in between the deep space missions. They had 165 F9 launches in 2025, each Starship carries more but I assume they're targeting 25+/year.
The depot, is it actually disposable or can it just hang out in space for a year like ISS until the next HLS mission? Once it's in place it's just a jerry can in space, it might just be that I'm a layman but I don't see anything that makes it a one off. Even if it has needs surely it can be maintained for significantly less than a new one. The only truly disposable part is the HLS itself.
In any case, none of this is specific for the Moon, it all applies for Mars too. So if you don't believe in SpaceX going beyond LEO, just say that. But that's a different tune than we've heard from most here before they pivoted to the Moon.