There is no point in dropping out unless you have a better plan that you are 100% certain you are going to have the motivation for.
Unless you want to spend your life working in Debenhams as a sales assistant, you HAVE to get qualifications, be they academic or high skilled vocational. There is simply no way around it. A maths degree will open up many potential career routes to you.
I would suggest you stick at it for the time being, whilst thinking more deeply about what kind of job you want to spend your life doing. Perhaps once you have a better idea of that, the maths degree won't seem so irrelevant and you will gain the motivation to work hard.