A lot of reasons.
Security: Even if your friend is decent at making websites, the odds are they do not have a bulk contract with a leading cyber-security firm to make your website hack proof. We employ the most modern security toolsets available to implement the latest security updates for all our client’s websites. We also offer physical and cloud backup and restore options.
SEO (Search Engine Optimisation): Your friend’s websites may be good, but are they optimised for search engines? Will your site come up in a google search ahead of competitors or even on the first page when potential customers search for your product or service? If your site is not professionally optimised you could be losing a lot of custom to competitors!!
Compliance with online payment standards: If you wish to accept payments via your website you will need it’s security to be PCI DSS (Payment Card Industry Data Security Standards) compliant. We can help with just that, and we suspect your friend can not!