Brian Sandberg said:
The secret, according to a bunch of indie dev Youtube channels, is to have multiple streams of revenue.
Nothing new about it, diversification is a millennia-old, well established truth.
I imagine It's only been somewhat recent, perhaps since the industrial era, where having a single job and single income source became the norm. Even if you weren't directly getting income from them, people would derive value from an abundance of skills. Some used for cash, others for barter or other social exchange.
In bigger business if you've only got a single project you're likely in trouble and need to either expand or die. I try to find companies that have at least 3 concurrent projects. Even if one slips or gets cancelled, there is enough other work to keep the business from failing. The other projects can help absorb the damage done, and if any one of them succeeds it can propel the business forward significantly.