I would never have confidence in my job security after negotiating a 50% raise with a competing offer.
I have negotiated some large increases in compensation in short period of times due to changing output and expectations from a role, but I feel like bringing a competing offer is inviting being replaced or made redundant, because companies don't want everyone to hold that level of negotiation over them just by saying "I could leave you know?"
Also, in my head, if they were underpaying me by 50%, I'd assume a big part of my value proposition was I cost 50% less than market rates.
And maybe this is even more paranoia, but I'd imagine a laser pointed at me and my performance afterwards, which ironically might end up affecting my performance (or at least my enjoyment of work)
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Also for context, I just accepted an offer from what will be my first company in a "superstar" city last week, even the signing + relocation bonus almost felt like life changing money compared to what I've made at other companies.
One big problem is companies are moving to "up and coming" cities then paying less based on cost of living... but the cost of living on those cities is rapidly rising due to their "up and coming" status, as more and more "superstars" move into the area.
So COL ends up rising faster than your salary unless you're on a seriously fast moving career path.