Your upgrade process is nothing short of extorsion. Don't think for a minute that any intelligent person would buy your reason why. Shame on you for ripping off clients
I, for one, would also like to save money on the software I trust and use.
The upgrade process ensures software compatibility and adopts the technology to give you the most accurate data.
If you don't use any of the add-on services in QuickBooks Desktop, your product will continue to work for personal needs. But, you'll not be able to subscribe to live technical support or any of the other Intuit services that can be integrated with QuickBooks Desktop. Please check this article: QuickBooks Desktop service discontinuation policy and upgrade information.
However, if you're being told to update to fix issues, there are some features that aren't available to the other QuickBooks version. Here's a link that you can compare: https://quickbooks.intuit.com/desktop/.
I have included these help articles in case you have other questions about QuickBooks.
Please let us know if you have any other concerns.I'll always be around to help.