I figured it was pretty obviously the rider that's making the bike not fall over, not the bike itself.
If the bike's ability to remain upright while moving was a natural feature, then why would you ever need to learn how to ride bikes? You could just sit on it and go if that was the case.
Accessibility. A blind person (or someone who just can't see that well, or who wants to read it at a different font and sizing level) has the opportunity to read this in text form with a screen reader or with adjusted view settings. But those don't work with images (screen readers may if the image has alt text).
Ease of search. If someone wanted to find this post down the line, they are not able to search the actual text of the post because it's an image.
Quality. In all honesty, what is gained by this post being an image instead of text? What is the visual element adding that couldn't be accomplished with italics and bolding?
Copy it and treat it as a quote in your written post (same place you put your source). You can add formatting to it if you want to emphasize parts.