The market for accessories such as screen protectors, cases and power banks in the US is now projected to attain a value of US$74.43 billion in 7 years. Headphones took the biggest piece (nearly 25%) of this space last year, and may maintain this share until 2026. However, the VR/AR headset sector is thought to be capable of the greatest growth into the next decade.
https://www.notebookcheck.net/The-US-phone-accessory-market-is-to-be-worth-US-74-billion-by-2026.429485.0.html