One way to think of the Ryanair "assessment" is that it is far from being the same as an "assessment" in other organisations. If you keep your wits about you it can be seen that hopes and expectations play an important role - the role that is played by a thing called "an employment contract" in most airlines.
The Ryanair assessment is part of a recruitment / business process which leads to you paying for a type-rating in the hope / expectation of a job. When you pay for that type-rating your money is gone - pass or fail. Also type-ratings are not provided by the airline, but by training intermediaries. You certainly will not be given a contact guaranteeing you employment. Assessment and providing type-rating to prospective pilot employees is not necessarily linked to employment in Ryanair.
Note that the sim type-rating check ride may not take place until a few weeks or - frequently - many months after you completed the simulator training for the rating. During that period you will be unpaid, but will be expected to turn up as and when required, pay for your hotel, etc. Being upaid continues until after your line training is almost finished.
All of this time - which many pilots report as taking well over a year - YOU fork out money, not them. When you get to see a contract and an employment reality that does not quite measure up to what you expected from the stories you heard. You also learn the bitter reality that you cannot do anything about the hole you find yourself in. Most find it easier to believe the stories about rapid promotion being the way to recover their financial situation.
When you go to EMA for your assessment try to find people who are well into this game and hear what they have to say. In particular try to find out just how many people have paid for a rating and are "awaiting line training" (there are a LOT). You can then do a bit of "assessing" for yourself.
What I can tell you is that there is no shortage of people prepared to sign up for this nonsense - which will help you self-justify doing exactly the same thing. Just pray that you don't become one of the losers in this little game - and there are most definitely are losers.
Remember that none of this is being done to help you get into aviation - Ryanair is exactly the opposite of helpful and philanthropic. Take a very hard look at what is on offer .... what is certain and what is unclear.