With $3bn budget you can replicate it in few months, promote for free using your own stronger brand and you're left with roughly $3bn in the bank to do whatever you want.
The real value lies in a successful execution, Windsurf is live and already has brand popularity with revenue stream. When it gets acquired by a titan, the die hard fans(vibe coders) will gain new trust that the product is not going anywhere and instead has solid future(we don’t yet know if oAI plans to do Msft style acquire, extend, kill yet). Cumulatively, this actually increases the value. Also Windsurf already has established enterprise revenue, hence brand trust and experience is already there.
In summary, an existing live and proven product is worth more any day over 100% uncertainty of building a sufficiently capable team to perfectly execute the same idea in specific deadline and also have the added burden of marketing, market penetration, user acquisition etc.
OpenAI has a much bigger brand.