InDesign 18.4 crashes on splashcreen

Further to @Rene Andritsch 

Reinstalling rarely fixes everything - you can do a complete reinstall using the
Creative Cloud Cleaner Tool https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html

Did you also log a bug report on the InDesign User Voice Forum? This way Adobe engineers will be more aware that you have troubles: https://indesign.uservoice.com/forums/601180-adobe-indesign-bugs

Also try “Resetting InDesign” outlined in this helpful article: https://community.adobe.com/t5/indesign-discussions/reset-indesign-preferences-and-other-troubleshooting/td-p/11990234