You're right in the sense that they need tens of billions of dollars which will be hard to raise.
However, I like to think about the technical details of their plan, because it's not just about them. It's about how it can be made to work; how the architecture could be improved, irrespective of the business model. Mars One may have taken the wrong approach, but this still offers an opportunity to generate ideas for how it might be done correctly in the future. That's interesting for me.
Regarding the money, there seems to be a lot of misunderstanding about how they have been raising money, particularly with regard to candidate contributions. These misunderstandings have largely been propagated by an ignorant media. Bas, and Mars One candidates such as Ryan MacDonald, have made efforts to rectify these misunderstandings. Sure, it's your right to not believe them and assume the worst of people, but I do not.