Gigabit isn't overkill for everyone, but it isn't necessary for everyone either. Whether it's worth it comes down to how many things are happening on your connection at once, not how impressive the number sounds.
One person streaming in HD and browsing needs a fraction of a gigabit. A household with multiple 4K streams running at once, a couple of people on video calls, someone gaming, and devices backing up in the background is a different story. Gigabit isn't about any single activity needing that much speed, it's about enough headroom that none of those things compete with each other.
The average home now runs 17 connected devices. Not all of them are demanding much bandwidth at the same time, but streaming, gaming, video calls, and cloud backups can stack up fast on a busy evening. If your household regularly has three or more of those happening simultaneously, gigabit gives you room to breathe. If it's mostly one or two people with staggered schedules, you'll likely use a fraction of a gigabit, and that's fine to say out loud.
4K streaming uses roughly 25 Mbps per stream. Even running several 4K streams at once, you're nowhere near a full gigabit. What gigabit buys you here isn't more speed than streaming requires, it's the buffer so streaming doesn't compete with everything else running in the house.
As we covered in our post on fiber and gaming, latency and jitter affect your match more than download speed does. Gigabit doesn't make your ping lower. What it does is keep your connection from getting squeezed when someone else in the house is doing something bandwidth-heavy at the same time.
Uploading your own content changes the math. Streaming gameplay, uploading large video files, or working from home with big file transfers benefits from symmetrical speeds, upload that matches download instead of crawling behind it the way it does on most cable plans.
If your household runs a lot at once, gigabit-class fiber earns its price.