It is not so much stupid but very boring -as it shows you did not read the full info and what is also told here in dozens of replies daily:
YOu can BOARD ANY train-in the system-untill 23.59 latest on 1 travelday and finish staying in THAT exact train till the trip ends. Even overnite trains that run untill the next day afternoon count as such.
Plus that now-august last month, here in DE there is the 9€ ticket-valid till 31/.8-and on ALL local transit-trains/trams/bus/metro-would also cover this trip. Trains here in DE are very often much delayed, overcrowded or sometimes cancelled due to giant demand and all kinds of problems-I can vouch for that too………..(though today it was happy travels nearly all day)