Start from arithmetic, not identity: your hourly value doing billable work versus the cost of competent help. An owner billing $150/hour who spends ten weekly hours fighting Google Ads is paying $6,000 a month for amateur marketing.
The hybrid that usually wins: own the strategy and the assets (accounts, site, lists, always), do the parts only you can do (reputation, referrals, being the face), and buy execution for the technical lanes where experience compounds, ads, tracking, deliverability.
Whichever way you go, the free-tools era means DIY is genuinely viable for the disciplined: the playbooks are public (ours literally are). The scarce ingredient isn't secrets. It's consistent weekly attention.