Most websites selling something, (product or service) typically focus most of their site around getting a user to convert the first time they hit the site. The challenge with this is that no matter how valuable your product or service is, it is very hard to get above a 3% ecommerce conversion rate unless you are a large trusted brand. However, if your only focus was to capture data of users coming to your site, (email, social interaction, cookies) you could get conversion rates in the 15-20% zone. Check out the math: If you can get to a 20% conversion on capturing data, with a strong remarking strategy (emails, retargeting, etc.) you may be able to convert a third of these in the coming months. Your net website conversion would now be 6.5% versus the 3% top out from getting direct transactions.
I am not saying not to try and capture the sale, my advice in most situations is to focus equally on both and have ways to track the remarking efforts to ensure that you are truly increasing your net conversion rate.