I like LibreOffice and I support it with donations too, but many people are already used to MS Office. And LibreOffice Calc, the one I use most, has big time usability problems and bugs. It doesn't have the same keyboard shortcuts as MS Excel. In fact, it chooses keyboard shortcuts that are very different from MS Excel, making usage even more cumbersome even though it hasn't adopted the Ribbon interface from MS and still has the standard pull down menus. It still doesn't have copy paste working well (sometimes, whatever I copy from another program cannot be pasted in it - this has been the case on Windows 7 and Windows 10 for at least a couple of years or longer across versions of LibreOffice 4.x/5.x). In my limited experience, there is no true competitor for MS Excel for those who have used MS Excel.