At some time or another, we all find we need to “call the guy.” That person, some tools, some skills, and some knowledge represent the magic that fixes whatever problem we were facing. Typically, this is in the context of doing some repairs to something that previously worked okay, but later broke. No matter how much some manufacturers would like us to purchase new items, there are many good reasons to repair instead of replace.
In pre-industrial times, the same situation applied, although the tools might have been a little simpler. Nonetheless the need for skills plus knowledge has been there since humans first made the simplest tools.
It is rare that you can have enough skills with one single tool to make a living. I don’t think I would hire a carpenter who advertised that he was a hammer guy, but explained he could bring along a separate saw guy, a drill guy, and a screwdriver guy.
It fascinates me the way businesses pop up (and sometimes disappear) with the intention to solve an extremely narrow problem. They will send out a guy with a limited toolkit, a little training, and a lot of marketing. They typically have identified a distinct problem and become convinced that their solution is the best and only choice. Mostly they are wrong.
The same concepts are perfectly applicable to new designs. As an engineer, you will call on knowledge and skills with various tools to become the guy. In other words, you will become the first person that your customers or your team calls to solve a particular type of problem or to help create a particular kind of design. Every problem or design completed will add to your knowledge and increase the probability that you will have a long and fruitful career.
However, you must make sure that you are always refreshing and expanding your knowledge and your skills. Imagine that you are a medieval calligrapher, painstakingly copying precious books, stroke-by-stroke with ink and parchment. Then somebody like Gutenberg comes along with a printing press and virtually wipes out demand for your skills and tools.
Remember that the business which employs you exists to solve problems for their customers. Don’t forget to keep an eye on trends within your overall industry and their customers. (For early warnings, sometimes you should be checking on trends among your customers’ customers.)
This also means constantly learning new tools; or at least new tricks for using your old tools. For electrical engineers, companies like Keysight and Tektronix offer lots of excellent resources online to help you understand their oscilloscopes and related tools. They have application notes and webinars to help you avoid the common mistakes using electronic tools. Many of the tool companies offer training for using their tools to improve the quality of your designs.
Remember that the ultimate skill is an ability to learn new skills. You can do it; so get back out there and fix something (again). Pretty soon, you will be the guy.