It's not impossible to be successful as a defendant in a civil suit representing yourself in the US, but I'm not sure the odds are good. The best case is if the judge immediately recognizes it as a specific kind of nuisance case that they've seen before, and is sympathetic to dismissing it as quickly as possible. In that case they might pretty strongly hint to you exactly what motions you need to file so they can get rid of the case. But it's also quite possible for a groundless case to not look obviously groundless if the defendant doesn't explain why well.
Were you by any chance in a civil-law country (most of Europe outside the UK)? The judges in civil-law systems take on more of a hybrid judge/investigator role, which makes it easier for them to play the role of helping out a defendant, if their investigation finds the facts warrant doing so. It's also more common for them to make decisions of their own accord, while the US norm is that the judges only rule on motions from the parties, rarely sua sponte. That makes it particularly important to file the right motions at the right times, to even give the judge a chance to rule in your favor.
Were you by any chance in a civil-law country (most of Europe outside the UK)? The judges in civil-law systems take on more of a hybrid judge/investigator role, which makes it easier for them to play the role of helping out a defendant, if their investigation finds the facts warrant doing so. It's also more common for them to make decisions of their own accord, while the US norm is that the judges only rule on motions from the parties, rarely sua sponte. That makes it particularly important to file the right motions at the right times, to even give the judge a chance to rule in your favor.