>>"Why would anyone turn down a 30% pay raise"
One of my friends here in Bangalore took a offer on those lines from a start up, around COVID. He realised instantly these things are for people with a life that is problem free, disease free, responsibilities free linear progression.
Soon enough his parents had to be hospitalised for big surgeries and he realised the start up comp had a near 0 health insurance cover. A decade's worth savings wiped clean in one go.
It took a while even for me to get to this realisation, if you have a good going, things are stable, office culture is good and friendly, and you have a comp that is better overalls. You are likely to do well in such a place on the longer run than jumping 10 places and realising the comp at a lot of places is just straight up fraud. They just cut things in one place and add some where else. In many cases the comp is bloated with big numbers but with a dozen ifs and buts(often company/team linked variable pay etc).
Eventually you could say that making rapid changes to a process doesn't necessarily add to bigger gains. You see this in the stock markets as well. Profit is inversely proportional to the quantity of trades you execute. Big gains come from stability and sticking to one winning formula for long. Same with health, relationships and jobs. Do more of that one thing that works. Don't try to do many such things that could work or mostly fail.