Maybe this won’t last forever. And of course lots of people got their fingers (and worse) burnt in the last .com fiasco. But because the cost of entry for digital stuff is low, and the technology is cheap (or rentable) it means that people are constantly looking for new ways to do new things, or better ways to do old things. And the scale of ideas can be smaller, it’s easy to start or evolve businesses using tools and services that are readily available online.
From what I’ve witnessed the structure of digital agencies tends to be more tolerant of these entrepreneurial tendencies. It’s not uncommon to find people running garage businesses, record labels, t-shirt companies, etc. I guess that’s partially a factor of scale. Small companies oddly seem to be able to cope with outside interests better. And partially it might be a factor of newness. Most digital agencies are <10 years old, so their founders can remember what it’s like to be young and motivated too.
Also many digital agencies were founded during a moment in time where stock options were everything. Microsoft receptionists were reportedly getting massive stock option payouts and everyone knew of someone who had just become a paper millionaire. Very few of them are actually millionaires anymore (paper or otherwise), but the spirit lives on.
A spirit of entrepreneurialism makes for an exciting environment to work in. One where transformative ideas, however stupid, are the thing that keeps everyone motivated.