I have seen some of my friends with awesome ideas struggle to convince people to get enough support to startup.
I am in agreement with David M. People also...
1. Are not always clear on what the limitations of the product are.
2. Make too many assumptions about the success of the business without any real proof.
3. People start a business, build a product WITHOUT asking their target base what it is they want. Very confusing and backwards to me. The Customer/Potential Customer/Partner, etc.. must always be asked for constructive feedback about the product.
The biggest issue I have when people pitch me on their ideas or startups is that they are not clear and concise. Next to that biggest mistakes (just a few):
1. Don't know their numbers or the many elements in their business plan.
2. They think that they have no competition or worse say they have no competitors. (there is ALWAYS competition)
3. State they only need to earn 1% of the market to be profitable but have no plan in place of how they will achieve that. (see lazy below)
4. Don't have a team that is competent or have not worked to build one.
5. Expect people to work for free or a ridiculously low compensation.
Same goes for if an entrepreneur is trying to build a team. Know what it is you want to build, the need it addresses, your own competencies and where the gaps are that you need to fill.
For me personally, don't come across as lazy. My personal nerve is hit when I talk to would be entrepreneurs who act like they have done all this work when in some cases they have done so little in the scheme of starting a business, or even worse they paid someone to do the work for them and are so lazy they can't even explain the work they paid someone else to do. That is probably the worse.
Now, the lazy element is not always the case. Many times, the entrepreneur just does not know how to proceed. For this, one is not lazy. BUT they must be willing to Aquire the needed partners.
I thing you need to do the right amount of honest market research into your product idea ,
1 who is the customer, can you actually speak with a number 10 - 20 of them ?
2 how are they currently dealing with this problem ?
3 how will your service save them time or money, make their life safer/better ?
do this work at least and you either have a business opportunity to make money or it is a vanity hobby that will be expensive .
if number 3 is not strong or can not be made it strong and you can not find people who you can not get to strongly agree with you then its most likely going to be an expensive hobby
as people mostly only pay for things that they really want and need