It's wrong to characterize it as "one person being the sole beneficiary of incoming businesses in India"

The recent spate of investments in Reliance JIO, have been just stake purchases. He is selling stake in his company to get capital for expansion.

Ambani has signaled that he wants investment to further grow an already rapidly growing empire of media services.

A few things are very favorable to Jio

a) Due to COVID and the expectation that this pandemic and its ripple effects will be felt for a few years, there is a very high likely hood that new customers will start consuming digital media services. And that is the key. Investments in JIO reflect the fact that it is the only company that has all it's cards right to capture the new user market.

b) Also, JIO has been at the cusp of an already rapidly increasing user base, that includes a large portion of rural people. It has seen a massive growth in user base and actual users too (No one is simply taking a phone connection and keeping it. They are actually using their JIO connections to consume content)

c) And the pandemic has come at just the right time too. Old guard companies are caught on backfoot. There is tremendous good will in people for JIO. JIO reduced costs 30X for data. It was a game changer. Peoples media consumption in India exploded.

d) In addition to this, Reliance group also has its hands in the Media and Entertainment industry. Not to mention retail, FMCG, etc.

So, as on date, JIO has the following services fully available to a large and every increasing base of users, this is apart from dead cheap 4G internet connectivity on phones and dongles.

1) Movies
2) TV Channels
3) Retail Shopping, they recently launched a competitor to Amazon.
4) Games
5) Educational content.

and a myriad more.

But here comes the best part. There are a couple of reasons India tailor made for services.

1. It has a large pre-teen, teen and young adult population, that will dominate consumer markets for at-least 5 decades.
2. It has 28 states, 122 major languages, and similar set of cultural groups. So you have ample amount of scope to localize content and have a good audience for that content.
3. Indians love to indulge in languages and cultures from other parts of India. Punjabi songs are loved all over the country. Telugu cinemas have huge markets in southern states. Tamil movies are revered all over the country. And Indians consume a lot of dubbed content. Including international ones, like Korean etc. So what this means is that media produced for one local culture / language, if received well, has a ready market all over India. This reduces risk and increases rewards.
4. Indians love to consume content. We are a noisy civilization. We consume a lot of content and want new content all the time. Movies are a huge part of the daily lives of rural villages.
5. Large number of people in rural areas have been using smartphones for the past 5 years, thanks to reducing handset costs and usage costs. They are already consuming content on the internet via Youtube, etc. They are a ready market to push content and services too.

I suspect JIO is looking for large investments to create new content for its media services and setup a distribution network for it's retail services.

Additionally, Reliance is highly respected in India. When the current CEOs father ran the company, millions of middle-class families in India bought houses, cars, got their children married, gathered retirement funds, etc riding on the sheer growth of Reliance as a company.

My father was also one of them.