It is still worth investing in a 4K Blu-ray player with Dolby Vision, even if your 4K TV doesn't support it. While your TV may not be able to take full advantage of the Dolby Vision technology, the player will still be able to upscale your Blu-ray discs to near 4K quality. Additionally, a 4K Blu-ray player with Dolby Vision will often have better sound quality and additional features such as support for streaming services.
Furthermore, investing in a 4K Blu-ray player with Dolby Vision can future-proof your home entertainment setup. As you upgrade your TV in the future, you'll be able to take full advantage of the player's capabilities. Plus, with the continued release of 4K Ultra HD discs, a 4K Blu-ray player will allow you to enjoy the best possible picture quality for your movie collection.
In summary, a 4K Blu-ray player with Dolby Vision is a worthwhile investment, even if your 4K TV doesn't support it, as it will provide improved picture and sound quality, and will future-proof your home entertainment setup.