Unlike science, Math has already been formed and developed. There isn't much you can "research". We shouldn't put money into something unnecessary when we can put it into disease research or other sciences. As for awdq21's point, is some partially useless mathematical theorem really purpose for spending money into researching maths? Really?
Mathematics is an important discipline because the natural sciences, to name one thing, benefit tremendously from it. However, hardly any of the abstract or pure mathematics has an application. How is Fermat's Last Theorem or the Poincaré Conjecture practically useful, despite the latter being a Millennium Prize Problem? G. H. Hardy himself said that pure mathematics has no practical use. Sure, number theory finally found an application in cryptography, but that is it.