I've been in multiple relationships by now but I pretty much never dated or only very sparsely through my 20s, depending on what you'd count. A few reasons:

• When I was younger online dating was much worse than today and had even fewer women, and I feel like approaching women in real life was much harder for several reasons, especially for me given my social anxiety, nerdiness, and lack of opportunity to cross paths with women in my life.
• Financial difficulties - I was living with my parents as an adult and was focused on fixing that situation, and was embarrassed/pessimistic about dating.
• I don't really fit in easily with the vast majority of people in terms of race, religion, activities, or attitudes about several things like money. It feels like race and religion have become less of an issue today, but I still struggle to find women I can relate to in terms of attitudes.
• Overall questionable appearance - OK physique but with bad hair and clothes.

Sidenote: One thing that annoys me is the attitude of measuring people, both men and women, by their level of relationship success. There's very little that's fair or rational about attraction, in fact it's the best example area where rationality would be almost entirely futile. So don't feel bad about it, just do what you want for yourself and ignore judgmental people.