It's pretty trivial to tell that a large portion of JWST's delays were related to the unfolding mechanism (first building it, then the 5 years of delays from a ripped sunshield, loose screws and more), much of which would be rendered unnecessary by Starship's wider payload bay. Thus of course it would've saved a ton of money on the telescope. The telescope wouldn't have needed so much testing if it didn't have 344 single points of failure, and it wouldn't have that many of those if it didn't need its unfolding mechanism.

If that isn't convincing enough, the budget plan including all folding mechanisms etc before testing was $6.5B, so the $3.5B extra was spent entirely on testing and repairs. Thus, if a folding mechanism was not needed, they could have saved at least that much on testing and fixing said mechanism.

Might be a good idea to take off your blinders before complaining about someone being more successful than you. Since your jealousy is blinding you so much, it would have been just as convenient for costs if any other rocket had a wider payload fairing than Ariane 5.