I think it is worth understanding that Crowdcube is not the same as Kickstarter, Pledge, etc. With the latter, you are basically lending funds to a project, easing cashflow, until you receive the goods or services promised. It's a form of pre-payment, usually with some perks to encourage you.
Crowdcube is equity crowd funding - in return for the funds, you receive a shareholding. Return on your investment will come if the business succeeds and decides to start paying dividends, or if the business in purchased by someone else in the future. It is certainly more speculative than a Kickstarter project.
In the UK and elsewhere, this form of business funding is growing very quickly, and is recognised as being a very legitimate method. It stems from the antipathy of our conventional banks for lending to small and medium sized businesses since the credit crunch. Crowdcube and other similar platforms have received regulatory approval from the Financial Services Authority.
Any business, when there is a need for more working capital to fund expansion, will have a number of options. Selling shares is one valid and popular way. The benefit to the original company shareholders is that they spread the risk... and in return, dilute their potential rewards. A new investor will understand that they are taking on risk, but consider it worthwhile if they think there's a good upside.
Crowdcube et al will have a detailed registration process, I presume, to meet regulatory requirements. The platforms need to know that you understand the risk profile of making these kinds of investments, and before they allow you to have detailed information concerning what are, after all, privately held companies. In a similar way, we would like gambling websites to have some controls to prevent kids betting.
Sorry for the "non-guitar" stuff - I just thought some explanation from a third party was in order.