In almost all cases the answer is no. The effort to retain a customer is normally a simpler task than the one involved in attracting a new client.
The exact comparison varies between sectors and businesses, but it’s almost always significantly easier and cheaper to retain existing customers than to find new ones.
Think about how much growth you’d generate if you got your customers to stay for just one extra month. Then think about what a few extra customer perks, offers or service improvements would cost to achieve this. Compare this to your marketing budget and returns, and you’ll get your answer.
Existing customers are also likely to be better for your business, as always chasing new ones risks increasing customer acquisition costs whilst with little visibility on the quality (however you might define this) of your userbase.