[...]
If the project of @Willi9974 is also based on the assumption that we increase the chances by mining for longer periods of time, then a lot of people might be loosing their money.
You seem to have something mixed up. Willi9974 meant the following: if you would for example mine with an existing total amount "x" with 25 PH/s hashrate for 6h duration, then the chances of a block hit are exactly the same as if you would mine with the same amount "x" with 50 PH/s for 3h duration, which with 5 PH/s hashrate for 30h duration. And this is a correct statement.
Solo mining as it is done here and also by Willi9984 is clear to everyone and should be considered gambling. You should only bet as much as you are willing to lose.
The values are derived from solochance.com. For further questions about the calculation and the background, you are welcome to contact the developer in this thread.