Because it’s fucking awesome. Here’s why I used* to use it:

• Built in email client
• Built in RSS reader.
• Themes and customisable UI (vertical tabs, bottom tags, tab previews, tab stacking)
• Built in ad blocker
• Sidebar with Mastodon, RSS, mail, translate, etc

*I use Floorp now cos I wanna support Mozilla/Firefox by upping the browser share numbers but Vivaldi is the best Chromium-based browser by far.