LinkedIn, Facebook/ Instagram and sometimes Google search ads to acquire new customer. Targeting the top 10 percent is possible in these media channels. Leverage remarketing to engage customers and then convert. LI and Google are expensive channels but can have high conversion rate.
If you have budgets advertise directly on moneycontrol from a brand building perspective.
Not sure if the HNIs have time to attend webinars. It is better to send someone to office.