Try not to think about it in terms of monetary gain. There are other issues at play here. The process only starts when people realize that the long term benefits outweigh the short-term, monetary gains. If people start reusing the bottles regularly, the cost of beer could actually start to go down because with every reuse, the brewer saves money. The more that brewer (or other reuse entity) reuses the bottles, the more the overhead cost is driven down, eventually allowing them to lower product cost.