A lot of people actually need the incomes that they get from working at these events - which is why they are going ahead.
The Indian cricketers complaints in Brisbane, was more about what they had been promised as their hotel and conditions and then weren't delivered e.g. that they would have access to the swimming pool and they weren't (and they were supposed to be the only people in the hotel). These guys had already done their 14 days hard lock down without complaining back in November but they weren't given what was promised when they agreed to go to Brisbane rather than stay in Sydney or return to Melbourne. Most of their complaints were met very quickly and they go on with the game.
The test in Brisbane was one of the greatest matches ever played and has be lauded around the cricket playing world. With the Indian cricket team you are talking about a world-wide audience of over 1 billion people and for many people this is an important aspect of their mental wellbeing - a time to forget their troubles and concentrate on something else.
The Aussie cricketers have already demanded that they get the vaccine first before they head off to South Africa for their tour there next month.
The difference between the cricketers and the tennis players is that the cricket teams can be put into a bubble and only have contact with each other while the tennis players are moving around and coming into contact with all sorts of people in different countries with different rules.
Well it seems the Oz Cricket team is about to go travelling to SA ..... so all sorts of people there in a different country with different rules

so not sure how this is "different" ..... maybe the tennis players should have traveled earlier to avoid a lockdown in weeks before their games or stayed home ...IMO they should all not travel at all .... it is all about money and championship points ....
The OZ cricket team will travel as a bubble and only come into contact with each other and the SA cricket team who are also in a bubble in preparation for this visit (or will be from at least 14 days before the tour begins).
The tennis players are individuals and they travel as individuals with their own support people. They have come from other tournaments as well which they usually play in a lead up to the Oz open.
The money that this event brings into Victoria is massive as well as the people who wouldn't have jobs it the tournament was cancelled. They seem to be forgotten - not the tennis players but the staff at the courts who serve the food or man the souvenir stands. For many of them their job is to work at the tennis and other sporting events and that is it.