Part of me is sad because change is hard and I thought I had become pretty good at what I do.

Don't doubt that at all. You are good at what you do. It's especially bad in tech and manufacturing, but it happens everywhere. My gf gave blood sweat and tears to a premier retailer for almost a decade of her life. She launched their brand in our state, traveled out of state to open other locations, grew the locations here, helped write the employee handbook, etc. She always met her numbers, scored perfectly on every secret shopper survey they ever sent her way, glowing reviews, -you name it. When the company screwed up and opened a second location right next to the original (they misread the lease and meant to transition from the first to the second, but the first still had a few years left on the lease when the new store opened), the sales numbers dropped as the customers split between the two locs (of course). They used that as an opportunity to fire her and replace her with someone making less than half her salary. She had become to good at what she did for her own good.

Anyway, it took her literally 3 or 4 years to get over that emotionally, because she really cared about that job. But it presented her with a choice: Where do I go from here? She couldn't imagine working elsewhere for much less pay and a brand she didn't love, so she opened her own clothing store instead with her life savings. She's working hard, but reaping the rewards now, many of the best ones are non-monetary. That doesn't mean it wasn't scary as hell for her and that there weren't bumps along the way. There are. But I think she's much happier now than she's ever been.

So I think your framing it as another opportunity is spot on. You're good at what you do, and I'm sure you're going to be showing a new group of people just how good you are.