Web development cost can be expensive and time consuming. The starting point to focus and reduce efforts is to understand your target consumers. The report of your visitors as a company is a good place to look for users insights including where and when came from.
Another thing is that the development cost for making a website well-matched with an old browser such as IE8 is high due to the fact that there are exceptions necessary for numerous levels of the user interface to cater for the lower abilities.
Moreover, you may be missing out on new developments available in the newest browsers, when a website compatible with old browsers is made because budget has been tilted to account for the small and continually retreating number of users. Many customers have been advised to remove the old IE8 browser from Microsoft from User Acceptance Testing the project developments, based on budget.