It has taught me that imposter syndrome fucking sucks.
On a more serious note, it’s taught me to be a solid ally for colleagues but always be skeptical of the business owners and decision makers themselves. I woke up to a layoff along with 5 other people and was laid off for 3 months before I found a new gig. Don’t allow emotions to cloud your job search. It’s all a negotiation and you should push for whatever you can get in terms of salary, PTO, etc. Never sell yourself short because the company sold you some story about how they need help.