Depends. If you go for the base model, yes. If you need more memory or a lot of fast storage or gobs of GPU horsepower or a lot of I/O, the 5800X will be definitely cheaper by a mile.

That being said, at the same config, the 5800X system would indeed only barely be cheaper.

I need lots of harddrives and pcie slots for my type of work. No matter how fast the M1 is, I'd rather use i3-10100 instead.

Sure, but this article helps answering "do I need both".