In 1997 I did a TT and placed about 39th out of a little over 400 people. I was riding a 16 year-old round-steel tube road bike with a total of 12 speeds. It was early in the riding season and my average speed was about 21.8 mph. Late that season just with more miles I was able to add another mph to that average over the same distance as the TT. I attribute it to being young and riding a lot of miles. I am sure if I had a state of the art bike and "aero" helmet and clothing etc. I could have gone a little faster yet, but I was never convinced going a bit faster was worth the cost to me, especially since every year or two the wealthy guys keep getting lighter more aero bikes and equipment, and to me that is buying speed, not having it innately or working for it. So don't compare yourself to the fast rich racers or pros, just see how you do against other people in your age group riding the same equipment you are riding and forget about the rest.
Now I am in my early 60s with heart problems and in a TT last year I averaged 19.5mph. The fastest kid, less than half my age, went 10mph and ten minutes faster in the same distance, I could care less. My interest was looking at how I did against other old geezers and especially the ones riding old bikes from the 1970s like I was, if I ran better than anyone younger or on newer equipment that was just a bonus. In my age and equipment class, I ran mid-pack or better, and that is just fine.
I just had a talk with a guy who literally grew up in the bicycle business, running a family bicycle shop his entire life he was born into, and he said as far as going fast on a bike goes, it is 90% rider, 10% bike, and I agreed with his assessment 100%. If I can get to the 90th-percentile of my age and equipment group without spending any cash on new equipment, then that is good enough for me, I will let those with less education and/or more money than they know what to do with have that top 10% if they need it that badly, I don't and never did and never will.