To reduce the amount of loss you can attack each of the points in the funnel where users abandon the road to the goal. Analyze them, AB-test potential solutions to figure out what works and what does not. Plugging a hole typically involves trying to state a testable hypothesis as to why your users are abandoning you, setting up a test case and running an AB test with the ‘original’ as the A and the new situation as the B. After a while (typically a few hundred conversions) you should have an idea if your analysis of the situation was correct. If it was and ‘B’ wins the day, B becomes the new situation and the cycle repeats.
Because of these tests funnels are typically instrumented and all kinds of intermediate goals are set.
Typically these intermediate goals are any of the following:
guest visits the site
guest interacts with the site
guest signs up for free membership
user interacts with the site
user hits ‘upsell’ page
user becomes a paying member
And possibly many steps in between.
Each of those conversion steps will lose a number of users, so that by the time you get to the bottom, the number of users left is likely only a very small fraction of the input at the top.
I know of one site that completely beats the odds here. Their conversion rate is absolutely stunning, close to 80%, they have only 50 visitors per day and, get this: almost everybody buys the product. In conversation, the owner of this site was talking to a big operator, someone whose websites have millions of visitors, and he was asked how big his website was. Oh, 50 per day or so. Wow said the big operator, 50K users per day, that’s impressive to leave the guy his ‘face’. No, the other one corrected him, 50 users per day.
Silence. So, how much money do you make, then? Oh, about 60K per month or so…
You don’t have to be really big if your conversion is stellar, conversely, those that are already visiting are already in your funnel, it is a lot easier (and probably less costly) to figure out how to make your site more appealing to the visitors you already have than to go and find more visitors.