There are a few reasons why people might choose to pay for 3D slicer software rather than using a free alternative, such as quality and reliability. In general, paid software tends to be of higher quality and more reliable than free software. This is because the developers of paid software have a financial incentive to ensure that their product is well-made and performs well.
At the moment of writing, there is only one slicer that I know is not free, and that is Simplify3D. The Simplify3D slicer is on the market for years, but at the end of 2022 it received a major update to version 5 and this update makes it up-to-par with the slicer alternatives that you can find in the free-to-use domain, but then the question remains, should you pay for it or use any of the free alternatives?
In general, I think that for hobby users with only one or just a couple of 3D printers, that do not produce 3D printed parts for a living, the free alternatives are good enough to work with. Software like Cura, Prusa slicer and such is very well made, and when you are not using batch processing or repeated printing functions, you should find no limitations in using this free slicer software.
Professional use: If you are using 3D slicer software for professional purposes, such as creating models for commercial use, you may be more likely to invest in a paid software product. This is because the cost of the software can be offset by the income you generate from your work.
It’s a fact that the batch processing functions and the possibility to change settings for different parts that are on the same print bed are not so good and easy to maintain in the free slicers and therefore, using Simplify3D is your only choice when you are using these functions a lot
Overall, whether or not to pay for 3D slicer software is a personal decision that depends on your needs and budget. If you are just starting out with 3D modeling and are not sure if it is something you want to pursue long-term, you might want to try out a free alternative first. On the other hand, if you are a professional or are planning to use 3D modeling extensively, a paid software product might be a better choice.
Get Simplify3D here: https://www.simplify3d.com/
I also made a video on my channel that explains why I am not upgrading to Simplify3D version 5