Updates have been numerous lately, and the fact that full upgrades are being used currently (full uninstall and reinstall), makes the process lengthy and verbose.
The updates have been numerous because the changes have been extensive and bugs have been found that needed to be fixed.
The full MSI upgrades has technical reasons and as soon as v2.5 stable is released, updates will stop and the upgrade process will first be improved before the first v2.6pre build (#21665).
v2.5 will soon reach stable.
Lastly, you can easily turn off auto-update by using the --skip-autoupdate startup parameter, yet this is really not advised due to improvements available in 2.5rc and the bugs that are being fixed with the updates.
Locked in endless update cycle
If you're locked in endless update cycle, remove all traces of SU, by uninstalling any installed version and deleting old shortcuts and folders.
Then install the latest available version from the Download section.