The (click:) macro is used to convert either a piece of text or a named hook into something that the reader can select.
The reasons each of you three (click:) macro examples don't work is as follows:
1. The macro accepts either a String (piece of text) or a hook name as a parameter to search for in the current Passage being shown, and you are passing a markup based link [[link1->example link text]] which is neither of these two things.
2. You are correctly passing the String value of "example link text" to the macro, but that text doesn't exist anywhere else in the current Passage so the macro can't find anything to convert into a link. The (go-to:) macro is expecting a String value (text wrapped in quotes) to be passed to it and you aren't doing that.
3. The (display:) macro is used to output the contents of a Passage on the current page being generated, and this output is the wrong type of value to be passing to the (click:) macro as something to search for. Again the (go-to:) macro is being passed the wrong type of value..
The simplest way to create a link that both assigns a variable to a variable and traverse to another Passage is to use the apply named (link:) macro.
(link: "example link text")[\
(set: $variable to it + 1)\
note: I added line-breaks and Escaped line break markup to the above example to make it more readable without adding extra lines to the page output.