Any cheap Hetzner dedicated (~30€/month) can handle tracking thousands of daily visits without breaking a sweat.
If we're talking about 10s of thousands, you're gonna need to invest in some SSD (€50-70/month probably).
If we're talking about dozens of sites, some of which have millions of yearly visitors (and a bunch of plugins and reports that need to be generated), then you're gonna encounter some issues and have to spend a considerable amount of time optimizing every part of it, and hardware cost will rise to a hundred or two per month.
To add another level: To track millions of requests per day for a couple of sites, it will probably cost around 1k - 5k per month, hosting on AWS. It's advised to use not the cheapeast hoster here, because any little outage directly affects every site that implements your tracking technology.
> It's advised to use not the cheapest hoster here, because any little outage directly affects every site that implements your tracking technology.
I guess it depends on how essential your tracking is, and how you've implemented it. It shouldn't be added in a way that can take out your site unless there is some business critical reason to track.
Then I'd ask, just how critical is the tracking? If losing a few hours of data is going to throw off your product development, do you have enough data to be making decisions? My experience is that bugs and misconfiguration of experiments is common in most orgs, so even if the system is up to capture all data, product managers check an experiment a week later to find they have only 50% of the data.
While it makes sense for some projects to use AWS, Azure, Google Cloud, etc, you could track the same number of requests on Digital Ocean, Vultr or Linode reliably and for less money.
If we're talking about 10s of thousands, you're gonna need to invest in some SSD (€50-70/month probably).
If we're talking about dozens of sites, some of which have millions of yearly visitors (and a bunch of plugins and reports that need to be generated), then you're gonna encounter some issues and have to spend a considerable amount of time optimizing every part of it, and hardware cost will rise to a hundred or two per month.