As Anne points out, crowdfunding isn't the same as charity (although charitable donations are a form of crowdfunding). It's a recognised form of alternative financing, outside the traditional financial system. The traditional financial system is often unwilling to invest in small businesses of any sort, and especially in creative arts, so they must look to other sources. In most cases the crowdfunder expects to receive some form of return for their investment, whether it's a copy of the final product, equity in the business, or interest on their investment. Like other forms of investment, there's a degree of risk.

How many CDs you expect to sell is irrelevant if you don't have the funds to make it in the first place. However if you don't expect to sell very many it is unlikely you'll attract many contributors. Crowdfunding is in effect advance sales, and resolves the cash-flow problem of having to pay all the recording, licencing and manufacturing costs up-front, before you have anything to sell.

Those of us with well-paid 'proper' day jobs and for whom music is a paying hobby may be able to fund an album from our own savings. Many others, especially those trying to make a full-time living from music, can't spare the cash for this.

As the person who introduced the question of 'virtue', let me say two things:

Firstly, some of the posts have implied that the answer is to cut corners and make it more cheaply. It is possible to make a CD relatively cheaply and with a competent sound engineer it should sound pretty good. However it will sound very much better if more time and resources can be devoted to it, and that costs money. "It's good enough for folk" is not, in my opinion, ever a good enough answer (with the possible exception of recordings of historic interest). The answer is to find a way to raise sufficient money to achieve the artist's vision.

The second point is that a number of the the replies seem to assume that crowdfunding is only being used be artists who are not really good enough, and who don't really deserve to be making a CD. This is far from the case. In fact the opposite is true - only artists who are good enough to generate enough sales will raise sufficient funding through any means, whether traditional loans or crowdfunding. Why would you invest in a project which you don't think will succeed? Vanity projects are unlikely to attract sufficient funding this way, and are most likely to have to rely on self-funding.