The cartoon above hopefully clarifies why some of us think that the expression of gratitude for one's own experience is problematic, when it posits God's direct and deliberate involvement in arranging circumstances for one's own benefit, while ignoring the contrasting experience of others and failing to offer a theological account of what befalls them in the same way one does for oneself.
Is it not better to simply express gratitude, rather than voicing the view that God is showing favoritism towards you, and is less kind towards those around you, in a way that may exacerbate the pain which those who are suffering feel?