An in-house development team can be a very effective way to develop your mobile product, but it’s also fraught with issues. Once you start your own team you are responsible for all the added hassle of creating a structure for them to thrive, and good developers can often be let down by poor infrastructure around them.
Hiring a development team means hiring project managers, dealing with retention, setting up Agile processes and often you’ll still find you need specialist knowledge that you need to source via a 3rd party.
Agencies have wider skillsets available to them and benefit from the economy of scale. Several different clients are splitting the cost of potentially expensive resource, which ultimately is a benefit that is passed onto you – getting expert advice at a fraction of the cost.
The downside is that you are not 100% in control of that resource – and paying for part of their time means you only get part of their time.
The other added benefits is that agencies will have experience building not just for your industry, but others as well. So beyond just the skill set you’re also tapping into potentially combined decades of experience and learnings that the developer can use to make your product even better.