When I started creating 3D environments 15 years ago the supply in terms of commercial textures and models was pretty meager. At the time this didn't feel like a big miss either, due to the low render resolution and lack of the now very popular raytracers you were used to a different way of building scenes.
Over the years this changed. More and more I was looking for a specific kind of texture for designing buildings. Where I couldn't find these on the online platforms I would go out and take pictures myself and then extract textures from them. Eventually, I continued to use certain textures often and sometimes added something new.
If there was a hiatus of a year or two you could very clearly see a change in style. This was often due to finding better fitting textures, using new techniques in Blender, and a new PC where I could incorporate more detail into the scenes. Until about 2015 I built scenes in a resolution of 1920x1080, then I switched to 4K where a new era in developing 3D environments began.
The higher resolution allowed everything to be seen in detail. Many models that worked well in HD did not look realistic in the higher resolution. I had to go out and refresh my collection. From that point on, the development of textures also went through a major evolution. Where I used to take a single shot of a wall or floor, I now went to work very precisely to get as much detail in the textures as possible.
With the advent of 3D photo scans, my technique soon became obsolete; the advent of true-to-life depth allowed me to rescan many of my popular textures. After a few years, I had a large collection of scans and was able to use them very effectively in the development of my 3D environments. Precisely because I had been looking for this specifically, it also fits very well into my collection. Sometimes I was looking for a certain type of stone for a long time, I visited many cities but finally found it at an abandoned ruin. So if you really want to get the most out of your scene you will have to go out sometimes.
But that's the fun part of this job, not everything can be found online, even though the supply sometimes seems enormous. It is also very satisfying to have your own collection that you can use to fill up your scene. You get a bond with your materials and that is important if you want to grow.
Therefore, if you are a beginning designer or have been in the business a bit longer, don't hesitate to go out and make your own materials. The end result will look a lot more unique and personal, besides that, it also has a great motivating role and it is adventurous.