You're a user but not your user
There are many times when you’re building things for people that are clearly very outside your own experience.
I’ve recently worked on a product for probation officers and people on probation. Something I had 0 experience of beforehand (Though as with anything, I love to get into the details and have a greater appreciation and understanding of it). But there are also times when the things we work on we a deep have an understanding of.
Buying things. I buy things. Driving. I drive. Things related to health. I have a mixed level understanding of the parts of health as a user (and having worked in and around health for 10 years lots of other understanding beyond being a user too).
These are more common or commodity things. Things like getting online, shopping, health.

With those there’s a chance, a good chance you’re a user too.
Personal first and second-hand experience and knowledge can be a powerful factor in helping creating better products and services. It’s why understanding context works. Why people who really know a thing can be so successful in creating new products.
But it doesn’t mean you’re your user.
If you work in tech or IT you’re probably already a different sort of user than another who doesn’t live or breathe digital services. What’s obvious to you may not be obvious elsewhere.
If you know what bandwidth or channel your WiFi router is on, you’re probably poorly placed to assume how people who don’t will understand and act.
This isn’t just a tech thing of course. Some of the greatest experts are often the poorest judges of the other needs and experiences of people. Knowing how stuff is made or the details can be very blinding to how other people understand or experience things. Or learn things.
I’ve lost count of the workshops I’ve been in where a technically accomplished person works on an assumption of their users having or easily getting the basics of a complex subject intuitively.
The answer is of course to develop a deep understanding of other users and note those common patterns. And to share and centre those stories strongly.
Not your own stories or preferences. You may be an outlier.
There are lots of things that annoy me about buying things online. But not all of them at scale will matter. Nor improve how successful an online shop is.
And who hasn’t spent time building a feature to resolve a marketing, sales or senior persons pet peeve or vision that had no relevance or impact on most user’s lives?
Even for passion projects. Unless you are literally the only person ever going to use it, your user is someone like you but not you.
So your experience matters. It can be useful. But it can hold you back or deflect a more important need. You’re a user, just not the user you should design for.