Why are so many long-shot Republicans running against Trump?

As of today, Trump seems well-positioned to win the Republican nomination.  The basic dynamic is familiar from 2016 – Trump has a strong base of committed supporters, the opposition will likely be divided, and many Republican primaries are winner-take-all or winner-take-most.  Couple this with the bump in support Trump got after his indictment in NY, the apparent missteps and general unlikeability of his chief rival DeSantis, and the fact that Trump seems to be running a functional campaign so far and it is hard to see much of a path for challengers. 

And yet large numbers of politicians who would be serious contenders in a pre-MAGA year are either running or teasing a run:  Pence, Christy, Haley, Sununu, Scott, Youngkin in addition to DeSantis, and maybe one or two others.  Why are they doing this?

The most important reason is that running for President is always a long shot, so if you want the job and can generate any interest in your campaign, you might as well throw your hat in the ring.  Fame is fleeting, conditions in 2028 or 2032 could easily be worse than they are today. 

This surely holds for DeSantis.  Until recently it seemed that he was keeping the option of not running open.  DeSantis is only 44.  Why not let Trump run and either win and be term-limited or lose and age out, and then pick up the mantle of MAGA-in-chief in 2028?  The main reason I suspect is that DeSantis could well be a flash in the pan and he knows it.  The MAGA movement could fade out, his brand of culture war MAGA-ism could face a backlash or just die a quiet death, something could go wrong in Florida, the Republican donor class could find a new horse to bet on . . . the list of hurdles is long.

Couple this with the real possibility that Trump will falter in some way and running makes sense even if it is difficult today to see a clear path for anyone other than DT.