take stuff apart and put it back together. install obscure operating systems. build a network and servers for just yourself. put multiple operating systems on the same computer. repair a broken laptop or phone. just fun things like that
Any pointers how to get into FreeBSD? I might need that for my game engine, especially as two of the main three consoles nowadays use some heavily modified versions of it (even if unfortunately I have to provide them as closed-source addons to the engine, since neither Sony nor Nintendo don't like open sourcing their stuff).
another easy way to get started is to install it in a VM. once you have the process down, you could try installing it to a secondary disk or partition on hardware.