A whole DVD only stores 4.7 gb, so a 5 gbps network is well fast enough. Maybe depends on your hardware. Netflix you need the top plan to get 4k streaming though.

A 4K blu-ray film is usually over 80 GB in disc quality.

It's not whether Gbps is fast enough, it's that the egress traffic for the streaming provider costs a lot of money, and they do everything they can to serve 1080p or 4k content that is actually much lower in quality than what we expect.

A lot of scenes look very impressive until you start seeing artifacts and hearing poor sound.

So how can you deal with Bluerays, let alone DVDs

Netflix has up to 16Mbps bitrate for its 4k video streams. Bluray is up to 128Mbps. That's a ton more space for avoiding compression artifacts, even though Bluray is lossless. Netflix compresses its video to shit so that it can save money on network costs. (https://www.flatpanelshd.com/news.php?subaction=showfull&id=...)

My subjective opinion is that Netflix has the worst video quality, though I've had some really bad experiences with Amazon Prime too. But Netflix is worse for me because some shows on Netflix can never get to the max bitrate they offer. For example, the last season of Peaky Blinders on 1080p Netflix had a ton of very noticeable compression artifacts, but that's not always the case for 1080p content. They just encoded it very poorly on the backend.

Apple TV+ has the best bitrate (up to 40Mbps), and Disney+ and HBO Max are decent as well.

Bluray is not lossless. Uncompressed 4k video streams are way over 10gbit range (it's a right pain)