I might be overestimating these costs, or I might not, only an F1 Team manager could tell us.
But the way I see it, stability in the regulations might be an easy way to a)save some money, b)level the field somewhat (eventually), c)lure new teams and sponsors, as:
a)evolving a design GRADUALLY over a long period of time (and as dictated by the competition) sounds to me cheaper than starting from scratch every year and then struggling to evolve said design ASAP within a very limited amount of time.
b)the big spenders would sooner rather than later end up in a position where they'd be squeezing 99.99% of the original design's performance, and then it would take a much longer process (and more expensive) to get that extra 0.01%, slowing the evolution process down and thus allowing the minor players to catch up eventually.
c)ANYBODY investing in ANYTHING wants SECURITY and STABILITY first. makes sense.
Of course, I'm not saying the rules would have to stay the same for ever..but what do I
The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents. H.P.Lovecraft