My wife and I have a fairly high NW yet I mow my own lawn, clean my own house, repair everything I can (thanks to YouTube), etc. but not sure I could live that extreme.
For me its a time > money equation. Right now, I have 3 little kids and I place a high value on supporting them as they are growing and don't want to miss a ton of memories from their childhood. It's a work/life balance for sure but I spend money to support there interests and I don't mind BTD on family vacations and outings.
We do somewhat watch our costs when shopping and I do a lot of things myself that I notice some of my neighbors hire out like lawn care, blowing my sprinkler system out, painting, gutter clearing, etc.
I did hire a plumber earlier this year when we had a sink backup that had consistently persisted to the point the plunger and snake weren't clearing the clog. Turns out the trap and some of the plumbing was slanted towards the disposal and had been caulked together so it required breaking the actual pipes and installing new ones. I am glad I didn't tackle that and the price to repair was fair considering the effort and expertise.
I also don't resurface my own asphalt drive, and usually find a deal under $325 for about 1250sq ft of surface. BUT I DO seal my concrete patio since its not as messy of a job and it's in the shade. I have much respect for those asphalt guys, its a dirty and HOT job with lots of self sufferings involved since I like it done on high temp days when the sealer really soaks in. The last 3 times I felt bad for the guy doing it as he is a little overweight which added ot his suffering but he seemed to enjoy his job and he did a good one so no discredit, just seemed like additional misery for him (I could be off on that though and everyone has their own story).
If my garage door spring breaks I will fix it myself. I've fixed my water heater, furnace, washer and dryer.
I hired out the deck build and patio build mainly because of the time factor again...but I did some of the finishing and prep work myself to save some money. Still ended up costing close to 40k though OUCH BTD.
As for Extreme ER, I want to live comfortably where my budget allows some cushion for surprise expenses. I do my own tree care, I could see that adding up quickly as we have a LOT of big tree's. I've saved thousands trimming and removing tree's that need it.
I do our own landscaping, and hauling of materials as I bought a dump trailer to haul mulch, rock, bricks etc. Replaced a few wood walls with brick. DW helps a LOT with the land/hardscape and now my son is getting old enough where he can help and does voluntarily lol.
DW does most of the indoor painting, she really enjoys it, but I will take outlets and other accessories off the walls for her and put them back on when she is done, clean out her brushes, buy the paint and supplies for her etc. We make a good team.
We do our own carpet cleaning, I see a lot of people hire that out. I bought my own Carpet Cleaner so I wouldn't need to hire it out. I sometimes do my own tire rotation, tire repair for nail holes and some mechanical work. I need to tackle an AC condenser, I was quoted around $650 to replace it and fill it with Chilling Freon...The parts to do the job are $75-140 plus tax for the condenser and 48oz of R-134A is about $72. Is it worth saving $500 in labor to do it myself. Probably. I already have all the tools to do the job. Even if it takes me 5 hours I am paying myself $100/hr instead of the mechanic.
Hard to tell what the future will hold, maybe all 3 of our kids live/move to different states so perhaps travel costs will be higher / more frequent than today. Gas will be more expensive, a given, taxes will be more expensive that's a given. As I age I might decide to hire out lawn care but maybe not...again hard to tell if the body will hold up over time, but hoping I have at least 30 to 40 more years of DIY. Once I am ER'd I will def attempt to do some of the repairs myself because I will have bought myself at min 40+ hrs of free time each week which is roughly an extra 2,000 hrs a year to get things done...but like I said for now time > money.
I want to get into cooking a bit more when I ER, making more elaborate dishes with more flavor...but with 3 kids a lot of times it seems like we are winging it to support the time they require to just get to our daily obligations. I think the key for me will be staying busy without BTD during ER. But if I can affort it then who cares.