Not at scale. 50TB per month is nothing. That’s 151mbps. Most transit providers will be okay with a 10% commitment, so this is a gigabit port which is like $60-300/mo.
Assuming 50 people would download the 1PB archive from the provider, that would require at least 151gbps of bandwidth, rounded up to 200gbps, at the cheapest transit provider (HE) this is still at least $12k/mo for transit alone.
Is that dirt-cheap for a non-profit? I’m not sure.
And if you did that with a consumer ISP, they would terminate you as a customer very quickly. At which point you’ll have to pay cloud provider for traffic, or a T1 network for IP transit (alongside colocation fees and actually putting a server in a datacenter and all that).
I also have several other unmetered gigabit links. The bandwidth is out there.
And there's an issue when you consider not all content in the archive is legal (both in terms of copyright and other types of illegal), cloud providers, a lot of other hosts will probably kick you off.