reasons i think that having a personal website is a good idea

• like minded people can quickly vibe check and learn a lot about you
• easy way to share ideas and send them to friends
• written log of your thoughts and posts, adds credibility when someone has been writing about something for x amount of years
• can show off your taste, you control how every part of the website functions and looks (if you don't thats a skill issue) can express more than just words (the goat of this is gwern
• high variance low stakes. pretty low stakes and easy to set up a personal website (takes 1 hr MAX), but adds the possiblity for some pretty cool tail end events e.g meet a future good friend, job offer, etc. high expected value activity imo.

you can find a record of the best personal websites i have found here