Just to be clear, delegating to vimm has a ROI. Every month the curation rewards are split between all delegators depending on the size of their delegation. This is calculated on a daily basis. So delegating for 5 days will give you something at the start of the next month.
For delegating 856 SP to vimm I get almost 3.5 SP back
Not the highest ROI but if you have some SP standing idle or you use VIMM yourself it is cool to make something on the side
This is calculated starting from a 25SP delegation so everyone can chip in :)