I have a 4plex with a coin op laundry. We have about $200 a month in revenue, I split it 70-30 with a leasing company so end up pocketing ~$130 a month. Expenses are about $80 a month so I end up netting about $50/month. It's not a huge money maker for me but $50 a month is a modest dinner out or a couple nice bottles of wine.
I would never recommend working with leasing companies unless you are a good negotiator. You will find weird things in your contract like it automatically renewing for long durations, the contract applying to owners, heirs and assigns (meaning it applies to future owners, whether they like it or not).
When I bought the 4plex, the previous owners negotiated a 15 year lease with a 50-50 split. The lease also automatically renewed for a subsequent 15 year term. I threatened to lock up their washers and driers in a closet unless they changed the terms. End result was a 30 month term, 70-30 split (in my favor) and I get to keep the washers at the end of the 30 months.
The real benefit is more for the tenants rather than for me. If I was serious about running a laundry facility, I'd go buy one. Until then, I'll enjoy the bottle of wine and dinner.