It has become very easy to start a URL Shortener! service, self-hosted and managed. I started to notice and increasing in such websites.
Some people do it for their own niche or a brand or for profiting from running ads on pages with redirect process.
However, striving for money made us deviate away from the real concept of a URL Shortener service, which is to shorten long links/urls.
Many people choose domain names that are longer than 4 leters and without the adition of a .com or longer such as .website and so on; it is better to go for a .io or .ly or .pw ; like mine ; TRG URL Shortener!, which is based on YOURLS! Script.
HAVE FUN