This is exactly the kind of thing that made me want to build this.
I think that your example is a good one for this: It is taking advantage of subsidies for 'luxury' by someone who can obviously afford to pay for his leisure activities.
And that's fine as long as there is nothing else left to spend public money on.
The whole train infrastructure is very self sufficient in Germany and they indeed export trains and tracks and all associated technology all over the place too, hence the term "oversufficient".
I don't know what the right balance is, but I do know it's not necessarily as simple as asking if all transport costs are met at the point of travel.
Even if it does provide more travel options, does that provide more value than it costs? I think that this is straightforward to answer.
I ask the same questions every time the topic pops up because all the praises in the comment tend to boils down to "it's good because it's cheaper". Sure everyone likes cheaper but that is not really a convincing argument.
At 99€ it would have massively lower user numbers. It's already to a large degree a commuter ticket at 49€ - at 99€ alternative tickets would be the better choice for many.
In any case, the point is that it is not clear to me what actual need this fulfills.
On regional trains you can travel Germany from north to south in less than 14 hours with 5 changes as opposed 8 hours with 2 changes for 125 EUR one-way on long-distance trains.
With the 49 EUR/month ticket you can hop off the train anytime you are tired of the journey. Can't do that with the 125 EUR one-time, one-way long-distance train ticket.
I totally see young and elderly people do this on regional trains.
People being able to move around easily would bring commerce to more areas. If 50 euros gets more people moving around and shopping at various places compared to 100 euro cutting that down by a lot.
I'd like to read arguments beyond "great, tickets are cheaper!".