I hate to burst your bubble, but it takes more than just hard work to be a Private banker. you need to have your client base first and the only way you can do it is to start in consumer bank or priority bank ( unless you have contacts that can give you USD 100M AUM)

Most Private bankers pay their dues and are in the market for at least 3 to 5 years minimum in order to make it to the level.

Still, no harm starting out as assistant, especially if you are assisting a Private banker who plans to retire and ultimately pass you his clients.