Background is no real barrier to an entry into SAP CRM. What matters is your commitment & your level of interest.
Though a lot of SAP CRM consultants come from an SD background, you will find a good sprinkling of consultants from backgrounds as diverse as technology, functional Sales, academics & even PhDs.
There is not much point in pursuing SAP CRM unless you are interested in it.
“Newbies” so often make the mistake of pursuing the area of SAP they think is hottest without regard to how their current industry strengths will play in SAP.
If you have an accounting background, you are far better off pursuing an SAP Financials career – even if your friend told you that SAP CRM was the hottest area in SAP.