I was lucky enough to learn how to program in Neuron Data's toolkits before the 1.0 release of the GUI components were released to the public. I rode that gravy train for about 15 years before the market imploded, with a peak of $120/hr. in the mid-late '90s.
But I didn't choose that route -- I got lucky that something I knew well turned out to have relatively high demand (at least compared to the number of people who really knew that tool well.) I could just have easily been unlucky enough to learn one of the other two GUI toolkits that Northern Telecom was evaluating at the time.
On the database front, I missed out -- I was tasked with evaluating the first release of Ingres, and have never seen that product again in my entire career. Fortunately I was able to wrangle some Oracle work and training with my Ingres SQL experience, and from there sidestepped to Sybase ASE, DB/2 LUW, and SQL Server. But I had to work at becoming an SQL expert (cross-platform); with the GUI tools, I just got lucky.
On the major downside, most of my GUI experience is now useless because the only place you'll find Neuron Data left in are old legacy/maintenance-mode applications. There is no new work being done with Open Interface Toolkit.