I`ld get a nice root server for so many users. I only have like 3000 Unique Visitors a day - and about 1TB of data downloads - besides sometimes on busy evening hearing complaints about download speed dropping down a bit the server (Core i7-6700, 64GB Ram, 512GB NVME Raid, plus 6TB HDD for the data downloads) the server is mainly just idling along - so I’m never CPU or RAM bound - using nginx and caching plugin (couldn’t get Varnish or a nice server based caching running properly). price at Hetzner 35€/months (39.99 including german VAT).
Yeah and I think the download speed is dropping a bit because Hetzner does not really give you 1Gbit/s dedicated but rather 300-400Mbit/s only after some burst time depending on your server rack you may be more or less lucky.
Maybe without all those downloads a hosted environment like Siteground on a big contract would be fine - and less work for maintenance. But then if you have some Linux experience running a root server is not much work (5-6 hours to setup for me, 20minutes maintenance per month). If you have lots of big downloads root server at least for downloads is a must anyhow. Hosting or Cloud simply is too expensive if your websites has about 300GB of downloadable data.