Given that its last raise was $15M (Canadian) in 2016 (https://www.crunchbase.com/organization/quandl#section-fundi...), and I haven't heard anything about Quandl since then, I'm guessing it's not a 10x exit.

That's probably fair. Quandl started by offering the "everyday" investor API access. I know the typical VC approach is to first get users and then scale, but often in investing/financial data products, it seems better to price high and then move down market. If you study the companies with the most success in the past (Bloomberg, CapIQ, MSCI, Eze, Advent, Factset, Morningstar, etc.), none of them started by trying to cater to the DIY investor.