Much of their model is hiring entry-level to junior resources, upskill them, bill them out to clients at high mark-ups. Many parts of the workforce follow an up-or-out mentality and technical/functional upskilling is a key component to this, rather than just tenure.
Purchasing a platform to train that many people is probably a bargain compared to what they are probably doing now -- letting everyone choose their own platform and reimbursing the retail cost.
It is definitely a bargain compared to what they did when I worked there -- they owned and operated an entire University-like campus called "St. Charles Illinois" and flew people in from all over the world.