To be fair, I think they are legitimate questions to ask when investing cash in someone else's business, as as soon as you have a product or service which is successful and is recognised by other companies they will try and enter the market, either to grow the market or to take your business.
The point that is missed though is that there are thousands of successful small to medium sized businesses that do survive and beat bigger competition either through superior products or more usually superior service and relationships with their customers. Assuming you do not have a unique product or service to offer and you can operate profitably at a sensible price point, the service levels and relationships you build with your clients are the key to business success.
To start a business from scratch is tough, but enormously rewarding. I would say you have to chose something you are exceptionally good at or have great knowledge, and/or have a huge passion for. Passion is the key though for me, without it you can not hope to succeed.
So start from this point - what are you good at? what are you passionate about?
Is there a business opportunity in those areas?
If so build a business plan - there's good information on The Prince's Trust website
http://www.princes-trust.org.uk/nee...t/business_plans/business_plan_templates.aspx
Other questions you need to consider:
What funding is required? Where will I get it from?
How can I pay my personal bills/feed the family/pay the mortgage in the early months?
Do I have the support of my family, particularly wife/husband/partner?
If you really want to do it, then do it. I've met many people over the years who say they want to start a business but years later still have not - for a multitude of reasons, some not their fault of course. Often people say it's not the right time, or this is wrong, the economy is bad etc etc. If you wait for perfect operating conditions then it will never happen.
It's not easy and there is no guarantee of success, however if you have the skills, funding and passion then it usually works and is far more rewarding in every sense than working for someone else.