Dealing with this in the heavy right now.
I've built a lot in my 10 years as a programmer. Infinitely, and automatically scaled application server based on load. Hasn't crashed or had a single downtime ever since release.
I've built mobile applications 100% myself being used by thousands still today.
I've learned 7 different programming languages. I've done web, mobile, server, and even bare metal firmware. The only 'domain' I haven't touched yet is ML.
Yet.... I truly feel DUMB. I feel like I'm nothing in this industry when one phone screen call puts you into an 'online assessment' where I can't solve the problem in better than O(N^2) time.
These fucking algorithms are killing me, and making me have a hard realization that maybe I'm just not cut out for this. Yea, I've built shit... but you know what... anyone could. I've plugged together a bunch of work other people did, and wallah, working server. Working app. Working whatever. But I can't write the libraries. I can't code a hyper scalable function that could handle petabytes of data.
The only reason my fucking amazing server hasn't crashed is because it doesn't handle anything close to the scale that many companies need. Hence why these algorithms are so important. But I can't fucking get better at them.