There are many benefits in embarking on a journey to building your smart home through automation. If I had to summarise the most important for me I’d go with the following list:
improved security: make your home a safer and securer place for you and your family automating alarm and surveillance systems, water/gas/smoke leaks (and any other tool that comes to your mind) so that no one has to think about arming them;
higher convenience: control (almost) everything from a single device you always have with you (your mobile!) and receive alerts for things that need your attention, even remotely;
better comfort: adapt lighting colour temperature throughout the day, start heating/cooling when coming home, use scenes for specific moments;
highest efficiency: save energy optimising usage of resources (especially electricity) with optimal scheduling of appliances and taking full advantage of any renewable source system you may have.
Additionally all the above mentioned could be achieved with systems like Home Assistant that put local control and privacy first, allowing also to integrate thousands of different devices you could already have.