They also require very different strengths & skillsets in founders. B2B products are usually sold, not bought. Sales skills in the founder are paramount, as well as a personality that can take rejection well and find win-wins and value-adds for the customer.
B2C products live and die by viral growth and word-of-mouth, because margins are not usually enough to support a consultative sales process or any sort of intensive advertising. That requires a founder that's really good at reading the zeitgeist and identifying needs that customers never knew they had, and that understands human psychology on an unconscious level. Often technical skills (on the founding team) matter more for B2C markets as well, because it's more critical to stand out from the competition.
Timing also matters more with B2C. There are some time periods (now, dot-com bust, or the late 80s & early 90s) where there are basically no viable B2C ideas available. There are also time periods (early 80s, dot-com boom, 2009-2013) where they are abundant. Unfortunately you often don't realize this until hindsight reveals all the people who kept working on their B2C ideas throughout the bust.
> There are some time periods (now, dot-com bust, or the late 80s & early 90s) where there are basically no viable B2C ideas available.
What leads you to believe that? I know plenty of people with healthy B2C businesses started recently. Heck, my business is B2C and while niche, it's viable for me.
But perhaps it's easier selling 300/mo to X businesses than selling to 5/mo to 60X consumers? You decide.