Bro, flying indoors takes lots of practice. My hobby before the Mavic Mini was flying 3D micro helicopters, indoors! So I've also crashed many times before, but that was long long ago! Nowadays I fly my Mavic Mini indoors all the time when the weather is Not Good to Fly on UAV Forecast, which has been most of the time. I got my Mini for Christmas and I've been flying it every single day since then Christmas until now, middle of February! I have not crashed my Mini even once, I haven't even come close to crashing it!
I still fly indoors everyday, if you want I can actually make a recording with the Mini of me flying indoors and show you what I mean! There is quite enough space to fly in my mini pent-house apartment! You just have to take is slow and easy, no crazy movements. Also if you have no experience flying in ATTI mode, then switch on as much lights in the room as you can, the more light on the floor that the mini can use to make out what's below it the more stable the lil fella will be! The bottom 2 sensors need quite a lot of light to work properly. Indoors there is no GPS probably, combine that with not enough light and the Mini will go in ATTI mode - where it will constantly need your input on the sticks, making tiny corrections just to keep it in one place!
I love to fly my Mini indoors - its just super awesome, but usually when I get to 60% from 100% at the start - the battery is just above 40C' and I'm at about just over 10 minutes into the flight - so I land the Mini wait for the battery to cool off as I have only one battery and I really wanna look after it as much as I can. This is also why I fly my drone every day, so that the battery get used and doesn't just stay charged. I will use storage voltage if I plan to not fly for a week or longer, but else I fly every day and I love it!
But flying indoors is my specialty, I love flying indoors and I do it every single day! Its very nice and safe, for me the safest flight I can have is an indoors flight - for sure! The drone will always be safe this way, can't lose it. If you fly it every day and you get used to ATTI mode then you will love to fly indoors! Flying indoors you just really gotta take it slow in the beginning. Just hover in the middle of the room first, and learn to do it till you're comfortable with hovering in one spot, then start to move around only. This is an expensive little machine so we have to respect it too much I think!
cool cool
PS: so I can make a video of me zipping indoors after work when I do my flights..