My guess as to why some Chelsea fans may not like him right now is mostly because we've been terrible since he took over. If we turn things around next season and return to being a force, then I suspect Boehly will be lauded by the SB faithful and all the pain of this season will be forgotten.
Let's face it, popularity in football is inextricably linked to on-field success.
You're most likely right, and Chelsea fans aren't exactly known for their patience and clear-mindedness, so it would be completely on brand for some of us to already dislike him before he's managed to get properly settled in.
When you take a step back from the everything and view the whole picture with everything that has happened from this time last year to now, it's a lot - Ukraine war, forced and hostile ownership change, lost key players to free agency, then the transfer window opened immediately after the takeover was complete and then first clashes with high ranking personnel hold over from the previous ownership and then coach fired whilst trying to rebuild a proper football structure from ground up. All of this in the span of about 4-5 months.
The mistake they made was trying to do too much too quickly. There was no need to spend 300m in the summer immediately after the takeover other than wanting to be seen making a statement to the fans. A more measured approach would have been much better but oh well, we're here now and hopefully with the structure now in place, if they get the right manager in (Luis Enrique), hopefully we'll start trending upwards.