If you look at the origin stories of many of the most commonly used software today, you’ll very often find someone at the root “who needed it for himself” (or herself). A very personal need turned into a product. As opposed to a company building something in-house or as their product.
This includes language (PHP, Perl, Python, Ruby) databases (Elasticsearch) tooling (git) browsers (mosaic/netscape/firefox) operating systems (Linux) and so forth.
So having personal tools, hacks and even entire suites is good for your own efficiency or work, it also lies at the root of many successful projects.