Almost 90% of mutual fund investments today happens through regular plans. In regular mutual funds, the distributor gets paid back up to 1.5% upfront and 1% end of every year as trail commission. Check this answer.
To give you an example, if you invest using regular plan (assuming a return of 15%), SIP of Rs 5000 for 25 years, the corpus at the end is 1.36 crores. If you do the same through direct, it can be Rs 1.64 crores. Whopping Rs 28 lks more. That is because in regular every year 1% goes away as commission, in direct it doesn’t.
Rs 50/month is the cost of subscribing to the direct platform. In the above example, for 25 years you would have paid around Rs 15000 in monthly fees as compared to regular plan where you could have potentially paid up to Rs 28lks.
Couple of other players who are offering direct (not with the convenience of demat) charge around Rs 1000 to Rs 2000 yearly with additional transaction charges.