The thing is that I can perfectly accept the posibility of serious irregularities during an election, it is something which is within the realm of the possible. So in my opinion, assuming Trump and his lawyers actually believed there was something fishy going on, they did good on going to judges and file lawsuits. Those are the regular channels which are supposed to be taken in the United States.
But Trump and his team could not bring any evidence on the table which could convince those judges (many of them appointed by Trump himself, by the way) so the lawsuits got dismissed and forgotten.
Who was at fault there?
If you file a lawsuit and have no evidence, you're at fault. Actually it was worse than that. Not only did they have no evidence but also got repeatedly scalded by multiple judges for being illiterate buffoons (well, maybe not quite in those words) for trivial things like not filing the appropriate paperwork and not-so-trivial things like putting people in danger with their frivolous lawsuits.
The legal system is not supposed to be used like that. It did work as designed (the lawsuits got dismissed) but still there was a lot of damage done by the reckless conspiratardery that these muppets tried to push.