Staying in the same job for too long, I felt comfortable and had lots of control over what I did but no job is forever and eventually it will end so be ready for it.

My skills atrophied so it was very hard to get a new job once I had to look for one.

Tech moves fast so you need to keep up to stay competitive or work your way up the career ladder. The best way is to look for a new job. If you're lucky you can do it within the same company.

Side note: I believed that by focusing on my tech skills, I would be promoted. Big mistake, tech skills are a small part. You need leadership and relationship skills which are a huge part of getting projects done.