Applied at IT company for Marketing Team Member

I’m 28 years old and currently feeling a heavy weight of regret over a job offer I declined about a year and a half ago. At that time, I was working at a marketing agency when an IT company approached me with an offer to join their marketing team. The offer was appealing: it came with better pay, the chance to work in-house—which I had been wanting—and the opportunity to gain experience in the tech industry. However, I let my insecurities take over. I convinced myself that I wouldn’t be able to handle the role with only two years of experience under my belt. I rationalized my decision by focusing on my stable job and the counteroffer my employer made, but deep down, I know I let fear dictate my choice. Now, I find myself still at the same agency, but the work environment has changed drastically for the worse. I’m unhappy and feel like I’ve outgrown my role. I’ve been trying to transition into an in-house position, but the job market is tight, and I’ve faced multiple rejections due to my lack of relevant in-house experience. It’s frustrating because I can’t help but think that if I had accepted that offer, I would have gained the experience I’m now being told I lack. I did manage to work with the IT company on a contract basis afterward, but when I asked about a full-time position later, they informed me that they had to cut jobs in favor of AI, and the person who took the role I rejected was laid off. I feel completely stuck and replay this decision in my mind daily. It’s affecting my personal life as well; I struggle to enjoy things because I feel so far behind in my career. I’m already in therapy, but I feel like I’m going in circles with this issue. I really need advice from anyone who has faced a similar situation. How did you move on from a career decision you regretted? How did you stop obsessing over what could have been?