I don’t think he was being thin-skinned, but rather curious to know the reasoning behind your statement.
If someone made a similar comment about why I get paid for the job I do, I would be keen to find out why they thought that way and try to provide some explanation.
The same question could be asked about why people would pay you to read about your mullet odyssey 
Although his statements may seem obvious or plain common sense to you, there are others who may (for what ever reason) be caught up in their current situation and aren’t able to see clearly enough to work their way out of it. Sometimes a comment or action from an external source is required to help break the thought cycle and allow for change to occur.