Is cheaper
Like any SaaS (Software-as-a-Service) service in the cloud, using it avoids the need and cost of keeping it in our own datacenter, which saves us hardware costs.
The recommendation is to have the monitoring system in a machine independent of the monitored systems since, for example, if we suffer problems in the storage of our virtualization system, the monitoring will also suffer and it is possible that it prevents us from being warned of this situation. As a note, this also applies to not hosting the monitoring system in the same cloud where we deploy our infrastructure.
In addition, and this is a constant, monitoring needs grow with the use of this and with the growth of the company itself and its services, so either we buy a hardware that we will barely take advantage of at first or we change as needed. In the cloud, this problem is solved by definition. And all this multiplies if we need high availability...
Naturally, other associated costs appear such as electricity consumption, equipment and cybersecurity personnel costs, space in our racks, etc., but perhaps the most important is maintenance and personnel costs: we need internal or external systems personnel who can implement and maintain the monitoring system. These personnel also need specific training in issues such as: maintenance of high load databases, high availability, parameterization of the software used, etc., and must also be up to date with these technologies to perform updates.
In many companies these profiles are not available and they are subcontracted to third parties who have to be given access to our systems for remote actions, they have to adapt and know our internal policies, etc. So, the result is usually not agile, a key factor if we do not want our monitoring system to become obsolete in the face of the rapid advance of new technologies such as containers, the cloud, etc.
Way much cheaper
If the company does have these profiles, in addition to its cost, there is another cost that is usually much higher, although difficult to measure, the opportunity cost: How much does it cost to have 2 engineers, 2 months building a monitoring system and spending X hours a month to maintain it while we could have them doing other projects that generate income for the company? Is the profile of a monitoring engineer useful for other developments or activities that generate income?
In addition, there is a terrible reality: an internally developed system normally means that it will be open to "change requests" of all kinds from internal customers, which will only increase the costs indicated above. This point is especially serious if our company is not even involved in the world of software development (for example, if we are a telecommunications operator). The difficulty of maintaining a system that gains complexity every day, change policies, deployments, documentation, training, etc. can bring out many costs that do not exist to outsource.
Faced with this, a SaaS provider in the cloud has optimized its operations to make massive, fast and tested updates, bearing in mind that its competitiveness as a service is based on its functionalities, as well as having the latest security patches immediately. In addition, we will benefit from the fact that your entire client portfolio is using the same software as us, so the detection of bugs, requests for functionalities and problems and their resolution will be much more agile and, on many occasions, transparent to us.