I've always wondered if Patreon's core business can ever be big enough to justify the VC and company size.

A generic 'patronage' business will always be expensive to develop and run compared with more targeted discovery and patronage platforms - music, video, podcast, porn. If I can see the 'patron early' videos in my normal youtube feed, or pay podcasters from my podcast app I'd use that. It takes a huge amount of effort to support 'long tail' artists - those that I'm not a mega fan of - on a different site.