The beauty of being a full-time developer is that if you put time in writing code, you're going to eventually get software. If your input is high quality, then you're going to get wonderful software. Your time is leveraged: you spend hours writing something and now an infinite number of people can use your work.
Your time is probably close to being just as leveraged if you are a designer or a PM: for example, you may have created and designed a UI guide used by your organization. Output is steady - much like a late-stage PE-backed business that consistently spins off cash, you know exactly what you're going to get.
Then there's the business side. You might have a hundred meetings and none turn into anything concrete. But you have to turn over these rocks to see if there's a bit of gold underneath one of them. And then one random meeting might turn into a life changing event, an offer to get funding from an investor, or a huge partnership deal. And that has a 100x impact on the business, more than making up for all of the previous "wasted" meetings. Output is lumpy - much like a VC's startup portfolio where one great deal can more than make up for a bunch of bad deals.
The obvious point is that across all roles there should be a sustained, high level of input - everyone should be working hard and finding more creative ways to leverage their time within their own job. The less obvious point is that across jobs, and perhaps also industries, there is naturally going to be variability in output. Understanding that and its consequences (e.g. how and when to smooth output) is valuable when running a company.
