I have to half-disagree with this, you CAN "sell" something that doesn't exist and sometimes it's a good way to test interest and ideas. You don't want to sell

I have to half-disagree with this, you CAN "sell" something that doesn't exist and sometimes it's a good way to test interest and ideas. You don't want to sell complete vapor (as in get a lot of interest then be like, oops now wait 4-5 months or whatever) but you don't want to build something that nobody wants or realize that people don't want it as badly as you thought they did.